Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761374Ab2BNXlA (ORCPT ); Tue, 14 Feb 2012 18:41:00 -0500 Received: from rcsinet15.oracle.com ([148.87.113.117]:17615 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757403Ab2BNXk6 (ORCPT ); Tue, 14 Feb 2012 18:40:58 -0500 From: Dan Magenheimer To: devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, linux-mm@kvack.org, ngupta@vflare.org, konrad.wilk@oracle.com, kurt.hackel@oracle.com, sjenning@linux.vnet.ibm.com, chris.mason@oracle.com, dan.magenheimer@oracle.com Subject: [PATCH 2/6] staging: ramster: local compression + tmem Date: Tue, 14 Feb 2012 15:35:42 -0800 Message-Id: <1329262542-25546-1-git-send-email-dan.magenheimer@oracle.com> X-Mailer: git-send-email 1.7.5.1 X-Source-IP: ucsinet21.oracle.com [156.151.31.93] X-CT-RefId: str=0001.0A090209.4F3AF0FE.00D6,ss=1,re=-6.500,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 88180 Lines: 3047 RAMster implements peer-to-peer transcendent memory, allowing a "cluster" of kernels to dynamically pool their RAM. This patch copies files from drivers/staging/zcache. RAMster compresses pages locally before transmitting them to another node, so we can leverage the zcache and tmem code directly. Note: there are no ramster-specific changes yet to these files. (Why copy? The ramster tmem.c/tmem.h changes are definitely shareable between zcache and ramster; the eventual destination for tmem.c is the linux lib directory. Ramster changes to zcache are more substantial and zcache is currently undergoing some significant unrelated changes (including a new allocator and breaking zcache-main.c into smaller files), so it seemed best to branch temporarily and merge later.) Signed-off-by: Dan Magenheimer --- drivers/staging/ramster/Kconfig | 13 + drivers/staging/ramster/Makefile | 3 + drivers/staging/ramster/tmem.c | 770 +++++++++++++ drivers/staging/ramster/tmem.h | 206 ++++ drivers/staging/ramster/zcache-main.c | 1988 +++++++++++++++++++++++++++++++++ 5 files changed, 2980 insertions(+), 0 deletions(-) create mode 100644 drivers/staging/ramster/Kconfig create mode 100644 drivers/staging/ramster/Makefile create mode 100644 drivers/staging/ramster/tmem.c create mode 100644 drivers/staging/ramster/tmem.h create mode 100644 drivers/staging/ramster/zcache-main.c diff --git a/drivers/staging/ramster/Kconfig b/drivers/staging/ramster/Kconfig new file mode 100644 index 0000000..7fabcb2 --- /dev/null +++ b/drivers/staging/ramster/Kconfig @@ -0,0 +1,13 @@ +config ZCACHE + tristate "Dynamic compression of swap pages and clean pagecache pages" + depends on CLEANCACHE || FRONTSWAP + select XVMALLOC + select LZO_COMPRESS + select LZO_DECOMPRESS + default n + help + Zcache doubles RAM efficiency while providing a significant + performance boosts on many workloads. Zcache uses lzo1x + compression and an in-kernel implementation of transcendent + memory to store clean page cache pages and swap in RAM, + providing a noticeable reduction in disk I/O. diff --git a/drivers/staging/ramster/Makefile b/drivers/staging/ramster/Makefile new file mode 100644 index 0000000..60daa27 --- /dev/null +++ b/drivers/staging/ramster/Makefile @@ -0,0 +1,3 @@ +zcache-y := zcache-main.o tmem.o + +obj-$(CONFIG_ZCACHE) += zcache.o diff --git a/drivers/staging/ramster/tmem.c b/drivers/staging/ramster/tmem.c new file mode 100644 index 0000000..1ca66ea --- /dev/null +++ b/drivers/staging/ramster/tmem.c @@ -0,0 +1,770 @@ +/* + * In-kernel transcendent memory (generic implementation) + * + * Copyright (c) 2009-2011, Dan Magenheimer, Oracle Corp. + * + * The primary purpose of Transcedent Memory ("tmem") is to map object-oriented + * "handles" (triples containing a pool id, and object id, and an index), to + * pages in a page-accessible memory (PAM). Tmem references the PAM pages via + * an abstract "pampd" (PAM page-descriptor), which can be operated on by a + * set of functions (pamops). Each pampd contains some representation of + * PAGE_SIZE bytes worth of data. Tmem must support potentially millions of + * pages and must be able to insert, find, and delete these pages at a + * potential frequency of thousands per second concurrently across many CPUs, + * (and, if used with KVM, across many vcpus across many guests). + * Tmem is tracked with a hierarchy of data structures, organized by + * the elements in a handle-tuple: pool_id, object_id, and page index. + * One or more "clients" (e.g. guests) each provide one or more tmem_pools. + * Each pool, contains a hash table of rb_trees of tmem_objs. Each + * tmem_obj contains a radix-tree-like tree of pointers, with intermediate + * nodes called tmem_objnodes. Each leaf pointer in this tree points to + * a pampd, which is accessible only through a small set of callbacks + * registered by the PAM implementation (see tmem_register_pamops). Tmem + * does all memory allocation via a set of callbacks registered by the tmem + * host implementation (e.g. see tmem_register_hostops). + */ + +#include +#include +#include + +#include "tmem.h" + +/* data structure sentinels used for debugging... see tmem.h */ +#define POOL_SENTINEL 0x87658765 +#define OBJ_SENTINEL 0x12345678 +#define OBJNODE_SENTINEL 0xfedcba09 + +/* + * A tmem host implementation must use this function to register callbacks + * for memory allocation. + */ +static struct tmem_hostops tmem_hostops; + +static void tmem_objnode_tree_init(void); + +void tmem_register_hostops(struct tmem_hostops *m) +{ + tmem_objnode_tree_init(); + tmem_hostops = *m; +} + +/* + * A tmem host implementation must use this function to register + * callbacks for a page-accessible memory (PAM) implementation + */ +static struct tmem_pamops tmem_pamops; + +void tmem_register_pamops(struct tmem_pamops *m) +{ + tmem_pamops = *m; +} + +/* + * Oid's are potentially very sparse and tmem_objs may have an indeterminately + * short life, being added and deleted at a relatively high frequency. + * So an rb_tree is an ideal data structure to manage tmem_objs. But because + * of the potentially huge number of tmem_objs, each pool manages a hashtable + * of rb_trees to reduce search, insert, delete, and rebalancing time. + * Each hashbucket also has a lock to manage concurrent access. + * + * The following routines manage tmem_objs. When any tmem_obj is accessed, + * the hashbucket lock must be held. + */ + +/* searches for object==oid in pool, returns locked object if found */ +static struct tmem_obj *tmem_obj_find(struct tmem_hashbucket *hb, + struct tmem_oid *oidp) +{ + struct rb_node *rbnode; + struct tmem_obj *obj; + + rbnode = hb->obj_rb_root.rb_node; + while (rbnode) { + BUG_ON(RB_EMPTY_NODE(rbnode)); + obj = rb_entry(rbnode, struct tmem_obj, rb_tree_node); + switch (tmem_oid_compare(oidp, &obj->oid)) { + case 0: /* equal */ + goto out; + case -1: + rbnode = rbnode->rb_left; + break; + case 1: + rbnode = rbnode->rb_right; + break; + } + } + obj = NULL; +out: + return obj; +} + +static void tmem_pampd_destroy_all_in_obj(struct tmem_obj *); + +/* free an object that has no more pampds in it */ +static void tmem_obj_free(struct tmem_obj *obj, struct tmem_hashbucket *hb) +{ + struct tmem_pool *pool; + + BUG_ON(obj == NULL); + ASSERT_SENTINEL(obj, OBJ); + BUG_ON(obj->pampd_count > 0); + pool = obj->pool; + BUG_ON(pool == NULL); + if (obj->objnode_tree_root != NULL) /* may be "stump" with no leaves */ + tmem_pampd_destroy_all_in_obj(obj); + BUG_ON(obj->objnode_tree_root != NULL); + BUG_ON((long)obj->objnode_count != 0); + atomic_dec(&pool->obj_count); + BUG_ON(atomic_read(&pool->obj_count) < 0); + INVERT_SENTINEL(obj, OBJ); + obj->pool = NULL; + tmem_oid_set_invalid(&obj->oid); + rb_erase(&obj->rb_tree_node, &hb->obj_rb_root); +} + +/* + * initialize, and insert an tmem_object_root (called only if find failed) + */ +static void tmem_obj_init(struct tmem_obj *obj, struct tmem_hashbucket *hb, + struct tmem_pool *pool, + struct tmem_oid *oidp) +{ + struct rb_root *root = &hb->obj_rb_root; + struct rb_node **new = &(root->rb_node), *parent = NULL; + struct tmem_obj *this; + + BUG_ON(pool == NULL); + atomic_inc(&pool->obj_count); + obj->objnode_tree_height = 0; + obj->objnode_tree_root = NULL; + obj->pool = pool; + obj->oid = *oidp; + obj->objnode_count = 0; + obj->pampd_count = 0; + (*tmem_pamops.new_obj)(obj); + SET_SENTINEL(obj, OBJ); + while (*new) { + BUG_ON(RB_EMPTY_NODE(*new)); + this = rb_entry(*new, struct tmem_obj, rb_tree_node); + parent = *new; + switch (tmem_oid_compare(oidp, &this->oid)) { + case 0: + BUG(); /* already present; should never happen! */ + break; + case -1: + new = &(*new)->rb_left; + break; + case 1: + new = &(*new)->rb_right; + break; + } + } + rb_link_node(&obj->rb_tree_node, parent, new); + rb_insert_color(&obj->rb_tree_node, root); +} + +/* + * Tmem is managed as a set of tmem_pools with certain attributes, such as + * "ephemeral" vs "persistent". These attributes apply to all tmem_objs + * and all pampds that belong to a tmem_pool. A tmem_pool is created + * or deleted relatively rarely (for example, when a filesystem is + * mounted or unmounted. + */ + +/* flush all data from a pool and, optionally, free it */ +static void tmem_pool_flush(struct tmem_pool *pool, bool destroy) +{ + struct rb_node *rbnode; + struct tmem_obj *obj; + struct tmem_hashbucket *hb = &pool->hashbucket[0]; + int i; + + BUG_ON(pool == NULL); + for (i = 0; i < TMEM_HASH_BUCKETS; i++, hb++) { + spin_lock(&hb->lock); + rbnode = rb_first(&hb->obj_rb_root); + while (rbnode != NULL) { + obj = rb_entry(rbnode, struct tmem_obj, rb_tree_node); + rbnode = rb_next(rbnode); + tmem_pampd_destroy_all_in_obj(obj); + tmem_obj_free(obj, hb); + (*tmem_hostops.obj_free)(obj, pool); + } + spin_unlock(&hb->lock); + } + if (destroy) + list_del(&pool->pool_list); +} + +/* + * A tmem_obj contains a radix-tree-like tree in which the intermediate + * nodes are called tmem_objnodes. (The kernel lib/radix-tree.c implementation + * is very specialized and tuned for specific uses and is not particularly + * suited for use from this code, though some code from the core algorithms has + * been reused, thus the copyright notices below). Each tmem_objnode contains + * a set of pointers which point to either a set of intermediate tmem_objnodes + * or a set of of pampds. + * + * Portions Copyright (C) 2001 Momchil Velikov + * Portions Copyright (C) 2001 Christoph Hellwig + * Portions Copyright (C) 2005 SGI, Christoph Lameter + */ + +struct tmem_objnode_tree_path { + struct tmem_objnode *objnode; + int offset; +}; + +/* objnode height_to_maxindex translation */ +static unsigned long tmem_objnode_tree_h2max[OBJNODE_TREE_MAX_PATH + 1]; + +static void tmem_objnode_tree_init(void) +{ + unsigned int ht, tmp; + + for (ht = 0; ht < ARRAY_SIZE(tmem_objnode_tree_h2max); ht++) { + tmp = ht * OBJNODE_TREE_MAP_SHIFT; + if (tmp >= OBJNODE_TREE_INDEX_BITS) + tmem_objnode_tree_h2max[ht] = ~0UL; + else + tmem_objnode_tree_h2max[ht] = + (~0UL >> (OBJNODE_TREE_INDEX_BITS - tmp - 1)) >> 1; + } +} + +static struct tmem_objnode *tmem_objnode_alloc(struct tmem_obj *obj) +{ + struct tmem_objnode *objnode; + + ASSERT_SENTINEL(obj, OBJ); + BUG_ON(obj->pool == NULL); + ASSERT_SENTINEL(obj->pool, POOL); + objnode = (*tmem_hostops.objnode_alloc)(obj->pool); + if (unlikely(objnode == NULL)) + goto out; + objnode->obj = obj; + SET_SENTINEL(objnode, OBJNODE); + memset(&objnode->slots, 0, sizeof(objnode->slots)); + objnode->slots_in_use = 0; + obj->objnode_count++; +out: + return objnode; +} + +static void tmem_objnode_free(struct tmem_objnode *objnode) +{ + struct tmem_pool *pool; + int i; + + BUG_ON(objnode == NULL); + for (i = 0; i < OBJNODE_TREE_MAP_SIZE; i++) + BUG_ON(objnode->slots[i] != NULL); + ASSERT_SENTINEL(objnode, OBJNODE); + INVERT_SENTINEL(objnode, OBJNODE); + BUG_ON(objnode->obj == NULL); + ASSERT_SENTINEL(objnode->obj, OBJ); + pool = objnode->obj->pool; + BUG_ON(pool == NULL); + ASSERT_SENTINEL(pool, POOL); + objnode->obj->objnode_count--; + objnode->obj = NULL; + (*tmem_hostops.objnode_free)(objnode, pool); +} + +/* + * lookup index in object and return associated pampd (or NULL if not found) + */ +static void **__tmem_pampd_lookup_in_obj(struct tmem_obj *obj, uint32_t index) +{ + unsigned int height, shift; + struct tmem_objnode **slot = NULL; + + BUG_ON(obj == NULL); + ASSERT_SENTINEL(obj, OBJ); + BUG_ON(obj->pool == NULL); + ASSERT_SENTINEL(obj->pool, POOL); + + height = obj->objnode_tree_height; + if (index > tmem_objnode_tree_h2max[obj->objnode_tree_height]) + goto out; + if (height == 0 && obj->objnode_tree_root) { + slot = &obj->objnode_tree_root; + goto out; + } + shift = (height-1) * OBJNODE_TREE_MAP_SHIFT; + slot = &obj->objnode_tree_root; + while (height > 0) { + if (*slot == NULL) + goto out; + slot = (struct tmem_objnode **) + ((*slot)->slots + + ((index >> shift) & OBJNODE_TREE_MAP_MASK)); + shift -= OBJNODE_TREE_MAP_SHIFT; + height--; + } +out: + return slot != NULL ? (void **)slot : NULL; +} + +static void *tmem_pampd_lookup_in_obj(struct tmem_obj *obj, uint32_t index) +{ + struct tmem_objnode **slot; + + slot = (struct tmem_objnode **)__tmem_pampd_lookup_in_obj(obj, index); + return slot != NULL ? *slot : NULL; +} + +static void *tmem_pampd_replace_in_obj(struct tmem_obj *obj, uint32_t index, + void *new_pampd) +{ + struct tmem_objnode **slot; + void *ret = NULL; + + slot = (struct tmem_objnode **)__tmem_pampd_lookup_in_obj(obj, index); + if ((slot != NULL) && (*slot != NULL)) { + void *old_pampd = *(void **)slot; + *(void **)slot = new_pampd; + (*tmem_pamops.free)(old_pampd, obj->pool, NULL, 0); + ret = new_pampd; + } + return ret; +} + +static int tmem_pampd_add_to_obj(struct tmem_obj *obj, uint32_t index, + void *pampd) +{ + int ret = 0; + struct tmem_objnode *objnode = NULL, *newnode, *slot; + unsigned int height, shift; + int offset = 0; + + /* if necessary, extend the tree to be higher */ + if (index > tmem_objnode_tree_h2max[obj->objnode_tree_height]) { + height = obj->objnode_tree_height + 1; + if (index > tmem_objnode_tree_h2max[height]) + while (index > tmem_objnode_tree_h2max[height]) + height++; + if (obj->objnode_tree_root == NULL) { + obj->objnode_tree_height = height; + goto insert; + } + do { + newnode = tmem_objnode_alloc(obj); + if (!newnode) { + ret = -ENOMEM; + goto out; + } + newnode->slots[0] = obj->objnode_tree_root; + newnode->slots_in_use = 1; + obj->objnode_tree_root = newnode; + obj->objnode_tree_height++; + } while (height > obj->objnode_tree_height); + } +insert: + slot = obj->objnode_tree_root; + height = obj->objnode_tree_height; + shift = (height-1) * OBJNODE_TREE_MAP_SHIFT; + while (height > 0) { + if (slot == NULL) { + /* add a child objnode. */ + slot = tmem_objnode_alloc(obj); + if (!slot) { + ret = -ENOMEM; + goto out; + } + if (objnode) { + + objnode->slots[offset] = slot; + objnode->slots_in_use++; + } else + obj->objnode_tree_root = slot; + } + /* go down a level */ + offset = (index >> shift) & OBJNODE_TREE_MAP_MASK; + objnode = slot; + slot = objnode->slots[offset]; + shift -= OBJNODE_TREE_MAP_SHIFT; + height--; + } + BUG_ON(slot != NULL); + if (objnode) { + objnode->slots_in_use++; + objnode->slots[offset] = pampd; + } else + obj->objnode_tree_root = pampd; + obj->pampd_count++; +out: + return ret; +} + +static void *tmem_pampd_delete_from_obj(struct tmem_obj *obj, uint32_t index) +{ + struct tmem_objnode_tree_path path[OBJNODE_TREE_MAX_PATH + 1]; + struct tmem_objnode_tree_path *pathp = path; + struct tmem_objnode *slot = NULL; + unsigned int height, shift; + int offset; + + BUG_ON(obj == NULL); + ASSERT_SENTINEL(obj, OBJ); + BUG_ON(obj->pool == NULL); + ASSERT_SENTINEL(obj->pool, POOL); + height = obj->objnode_tree_height; + if (index > tmem_objnode_tree_h2max[height]) + goto out; + slot = obj->objnode_tree_root; + if (height == 0 && obj->objnode_tree_root) { + obj->objnode_tree_root = NULL; + goto out; + } + shift = (height - 1) * OBJNODE_TREE_MAP_SHIFT; + pathp->objnode = NULL; + do { + if (slot == NULL) + goto out; + pathp++; + offset = (index >> shift) & OBJNODE_TREE_MAP_MASK; + pathp->offset = offset; + pathp->objnode = slot; + slot = slot->slots[offset]; + shift -= OBJNODE_TREE_MAP_SHIFT; + height--; + } while (height > 0); + if (slot == NULL) + goto out; + while (pathp->objnode) { + pathp->objnode->slots[pathp->offset] = NULL; + pathp->objnode->slots_in_use--; + if (pathp->objnode->slots_in_use) { + if (pathp->objnode == obj->objnode_tree_root) { + while (obj->objnode_tree_height > 0 && + obj->objnode_tree_root->slots_in_use == 1 && + obj->objnode_tree_root->slots[0]) { + struct tmem_objnode *to_free = + obj->objnode_tree_root; + + obj->objnode_tree_root = + to_free->slots[0]; + obj->objnode_tree_height--; + to_free->slots[0] = NULL; + to_free->slots_in_use = 0; + tmem_objnode_free(to_free); + } + } + goto out; + } + tmem_objnode_free(pathp->objnode); /* 0 slots used, free it */ + pathp--; + } + obj->objnode_tree_height = 0; + obj->objnode_tree_root = NULL; + +out: + if (slot != NULL) + obj->pampd_count--; + BUG_ON(obj->pampd_count < 0); + return slot; +} + +/* recursively walk the objnode_tree destroying pampds and objnodes */ +static void tmem_objnode_node_destroy(struct tmem_obj *obj, + struct tmem_objnode *objnode, + unsigned int ht) +{ + int i; + + if (ht == 0) + return; + for (i = 0; i < OBJNODE_TREE_MAP_SIZE; i++) { + if (objnode->slots[i]) { + if (ht == 1) { + obj->pampd_count--; + (*tmem_pamops.free)(objnode->slots[i], + obj->pool, NULL, 0); + objnode->slots[i] = NULL; + continue; + } + tmem_objnode_node_destroy(obj, objnode->slots[i], ht-1); + tmem_objnode_free(objnode->slots[i]); + objnode->slots[i] = NULL; + } + } +} + +static void tmem_pampd_destroy_all_in_obj(struct tmem_obj *obj) +{ + if (obj->objnode_tree_root == NULL) + return; + if (obj->objnode_tree_height == 0) { + obj->pampd_count--; + (*tmem_pamops.free)(obj->objnode_tree_root, obj->pool, NULL, 0); + } else { + tmem_objnode_node_destroy(obj, obj->objnode_tree_root, + obj->objnode_tree_height); + tmem_objnode_free(obj->objnode_tree_root); + obj->objnode_tree_height = 0; + } + obj->objnode_tree_root = NULL; + (*tmem_pamops.free_obj)(obj->pool, obj); +} + +/* + * Tmem is operated on by a set of well-defined actions: + * "put", "get", "flush", "flush_object", "new pool" and "destroy pool". + * (The tmem ABI allows for subpages and exchanges but these operations + * are not included in this implementation.) + * + * These "tmem core" operations are implemented in the following functions. + */ + +/* + * "Put" a page, e.g. copy a page from the kernel into newly allocated + * PAM space (if such space is available). Tmem_put is complicated by + * a corner case: What if a page with matching handle already exists in + * tmem? To guarantee coherency, one of two actions is necessary: Either + * the data for the page must be overwritten, or the page must be + * "flushed" so that the data is not accessible to a subsequent "get". + * Since these "duplicate puts" are relatively rare, this implementation + * always flushes for simplicity. + */ +int tmem_put(struct tmem_pool *pool, struct tmem_oid *oidp, uint32_t index, + char *data, size_t size, bool raw, bool ephemeral) +{ + struct tmem_obj *obj = NULL, *objfound = NULL, *objnew = NULL; + void *pampd = NULL, *pampd_del = NULL; + int ret = -ENOMEM; + struct tmem_hashbucket *hb; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + obj = objfound = tmem_obj_find(hb, oidp); + if (obj != NULL) { + pampd = tmem_pampd_lookup_in_obj(objfound, index); + if (pampd != NULL) { + /* if found, is a dup put, flush the old one */ + pampd_del = tmem_pampd_delete_from_obj(obj, index); + BUG_ON(pampd_del != pampd); + (*tmem_pamops.free)(pampd, pool, oidp, index); + if (obj->pampd_count == 0) { + objnew = obj; + objfound = NULL; + } + pampd = NULL; + } + } else { + obj = objnew = (*tmem_hostops.obj_alloc)(pool); + if (unlikely(obj == NULL)) { + ret = -ENOMEM; + goto out; + } + tmem_obj_init(obj, hb, pool, oidp); + } + BUG_ON(obj == NULL); + BUG_ON(((objnew != obj) && (objfound != obj)) || (objnew == objfound)); + pampd = (*tmem_pamops.create)(data, size, raw, ephemeral, + obj->pool, &obj->oid, index); + if (unlikely(pampd == NULL)) + goto free; + ret = tmem_pampd_add_to_obj(obj, index, pampd); + if (unlikely(ret == -ENOMEM)) + /* may have partially built objnode tree ("stump") */ + goto delete_and_free; + goto out; + +delete_and_free: + (void)tmem_pampd_delete_from_obj(obj, index); +free: + if (pampd) + (*tmem_pamops.free)(pampd, pool, NULL, 0); + if (objnew) { + tmem_obj_free(objnew, hb); + (*tmem_hostops.obj_free)(objnew, pool); + } +out: + spin_unlock(&hb->lock); + return ret; +} + +/* + * "Get" a page, e.g. if one can be found, copy the tmem page with the + * matching handle from PAM space to the kernel. By tmem definition, + * when a "get" is successful on an ephemeral page, the page is "flushed", + * and when a "get" is successful on a persistent page, the page is retained + * in tmem. Note that to preserve + * coherency, "get" can never be skipped if tmem contains the data. + * That is, if a get is done with a certain handle and fails, any + * subsequent "get" must also fail (unless of course there is a + * "put" done with the same handle). + + */ +int tmem_get(struct tmem_pool *pool, struct tmem_oid *oidp, uint32_t index, + char *data, size_t *size, bool raw, int get_and_free) +{ + struct tmem_obj *obj; + void *pampd; + bool ephemeral = is_ephemeral(pool); + int ret = -1; + struct tmem_hashbucket *hb; + bool free = (get_and_free == 1) || ((get_and_free == 0) && ephemeral); + bool lock_held = false; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + lock_held = true; + obj = tmem_obj_find(hb, oidp); + if (obj == NULL) + goto out; + if (free) + pampd = tmem_pampd_delete_from_obj(obj, index); + else + pampd = tmem_pampd_lookup_in_obj(obj, index); + if (pampd == NULL) + goto out; + if (free) { + if (obj->pampd_count == 0) { + tmem_obj_free(obj, hb); + (*tmem_hostops.obj_free)(obj, pool); + obj = NULL; + } + } + if (tmem_pamops.is_remote(pampd)) { + lock_held = false; + spin_unlock(&hb->lock); + } + if (free) + ret = (*tmem_pamops.get_data_and_free)( + data, size, raw, pampd, pool, oidp, index); + else + ret = (*tmem_pamops.get_data)( + data, size, raw, pampd, pool, oidp, index); + if (ret < 0) + goto out; + ret = 0; +out: + if (lock_held) + spin_unlock(&hb->lock); + return ret; +} + +/* + * If a page in tmem matches the handle, "flush" this page from tmem such + * that any subsequent "get" does not succeed (unless, of course, there + * was another "put" with the same handle). + */ +int tmem_flush_page(struct tmem_pool *pool, + struct tmem_oid *oidp, uint32_t index) +{ + struct tmem_obj *obj; + void *pampd; + int ret = -1; + struct tmem_hashbucket *hb; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + obj = tmem_obj_find(hb, oidp); + if (obj == NULL) + goto out; + pampd = tmem_pampd_delete_from_obj(obj, index); + if (pampd == NULL) + goto out; + (*tmem_pamops.free)(pampd, pool, oidp, index); + if (obj->pampd_count == 0) { + tmem_obj_free(obj, hb); + (*tmem_hostops.obj_free)(obj, pool); + } + ret = 0; + +out: + spin_unlock(&hb->lock); + return ret; +} + +/* + * If a page in tmem matches the handle, replace the page so that any + * subsequent "get" gets the new page. Returns 0 if + * there was a page to replace, else returns -1. + */ +int tmem_replace(struct tmem_pool *pool, struct tmem_oid *oidp, + uint32_t index, void *new_pampd) +{ + struct tmem_obj *obj; + int ret = -1; + struct tmem_hashbucket *hb; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + obj = tmem_obj_find(hb, oidp); + if (obj == NULL) + goto out; + new_pampd = tmem_pampd_replace_in_obj(obj, index, new_pampd); + ret = (*tmem_pamops.replace_in_obj)(new_pampd, obj); +out: + spin_unlock(&hb->lock); + return ret; +} + +/* + * "Flush" all pages in tmem matching this oid. + */ +int tmem_flush_object(struct tmem_pool *pool, struct tmem_oid *oidp) +{ + struct tmem_obj *obj; + struct tmem_hashbucket *hb; + int ret = -1; + + hb = &pool->hashbucket[tmem_oid_hash(oidp)]; + spin_lock(&hb->lock); + obj = tmem_obj_find(hb, oidp); + if (obj == NULL) + goto out; + tmem_pampd_destroy_all_in_obj(obj); + tmem_obj_free(obj, hb); + (*tmem_hostops.obj_free)(obj, pool); + ret = 0; + +out: + spin_unlock(&hb->lock); + return ret; +} + +/* + * "Flush" all pages (and tmem_objs) from this tmem_pool and disable + * all subsequent access to this tmem_pool. + */ +int tmem_destroy_pool(struct tmem_pool *pool) +{ + int ret = -1; + + if (pool == NULL) + goto out; + tmem_pool_flush(pool, 1); + ret = 0; +out: + return ret; +} + +static LIST_HEAD(tmem_global_pool_list); + +/* + * Create a new tmem_pool with the provided flag and return + * a pool id provided by the tmem host implementation. + */ +void tmem_new_pool(struct tmem_pool *pool, uint32_t flags) +{ + int persistent = flags & TMEM_POOL_PERSIST; + int shared = flags & TMEM_POOL_SHARED; + struct tmem_hashbucket *hb = &pool->hashbucket[0]; + int i; + + for (i = 0; i < TMEM_HASH_BUCKETS; i++, hb++) { + hb->obj_rb_root = RB_ROOT; + spin_lock_init(&hb->lock); + } + INIT_LIST_HEAD(&pool->pool_list); + atomic_set(&pool->obj_count, 0); + SET_SENTINEL(pool, POOL); + list_add_tail(&pool->pool_list, &tmem_global_pool_list); + pool->persistent = persistent; + pool->shared = shared; +} diff --git a/drivers/staging/ramster/tmem.h b/drivers/staging/ramster/tmem.h new file mode 100644 index 0000000..ed147c4 --- /dev/null +++ b/drivers/staging/ramster/tmem.h @@ -0,0 +1,206 @@ +/* + * tmem.h + * + * Transcendent memory + * + * Copyright (c) 2009-2011, Dan Magenheimer, Oracle Corp. + */ + +#ifndef _TMEM_H_ +#define _TMEM_H_ + +#include +#include +#include +#include + +/* + * These are pre-defined by the Xen<->Linux ABI + */ +#define TMEM_PUT_PAGE 4 +#define TMEM_GET_PAGE 5 +#define TMEM_FLUSH_PAGE 6 +#define TMEM_FLUSH_OBJECT 7 +#define TMEM_POOL_PERSIST 1 +#define TMEM_POOL_SHARED 2 +#define TMEM_POOL_PRECOMPRESSED 4 +#define TMEM_POOL_PAGESIZE_SHIFT 4 +#define TMEM_POOL_PAGESIZE_MASK 0xf +#define TMEM_POOL_RESERVED_BITS 0x00ffff00 + +/* + * sentinels have proven very useful for debugging but can be removed + * or disabled before final merge. + */ +#define SENTINELS +#ifdef SENTINELS +#define DECL_SENTINEL uint32_t sentinel; +#define SET_SENTINEL(_x, _y) (_x->sentinel = _y##_SENTINEL) +#define INVERT_SENTINEL(_x, _y) (_x->sentinel = ~_y##_SENTINEL) +#define ASSERT_SENTINEL(_x, _y) WARN_ON(_x->sentinel != _y##_SENTINEL) +#define ASSERT_INVERTED_SENTINEL(_x, _y) WARN_ON(_x->sentinel != ~_y##_SENTINEL) +#else +#define DECL_SENTINEL +#define SET_SENTINEL(_x, _y) do { } while (0) +#define INVERT_SENTINEL(_x, _y) do { } while (0) +#define ASSERT_SENTINEL(_x, _y) do { } while (0) +#define ASSERT_INVERTED_SENTINEL(_x, _y) do { } while (0) +#endif + +#define ASSERT_SPINLOCK(_l) WARN_ON(!spin_is_locked(_l)) + +/* + * A pool is the highest-level data structure managed by tmem and + * usually corresponds to a large independent set of pages such as + * a filesystem. Each pool has an id, and certain attributes and counters. + * It also contains a set of hash buckets, each of which contains an rbtree + * of objects and a lock to manage concurrency within the pool. + */ + +#define TMEM_HASH_BUCKET_BITS 8 +#define TMEM_HASH_BUCKETS (1<persistent) +#define is_ephemeral(_p) (!(_p->persistent)) + +/* + * An object id ("oid") is large: 192-bits (to ensure, for example, files + * in a modern filesystem can be uniquely identified). + */ + +struct tmem_oid { + uint64_t oid[3]; +}; + +static inline void tmem_oid_set_invalid(struct tmem_oid *oidp) +{ + oidp->oid[0] = oidp->oid[1] = oidp->oid[2] = -1UL; +} + +static inline bool tmem_oid_valid(struct tmem_oid *oidp) +{ + return oidp->oid[0] != -1UL || oidp->oid[1] != -1UL || + oidp->oid[2] != -1UL; +} + +static inline int tmem_oid_compare(struct tmem_oid *left, + struct tmem_oid *right) +{ + int ret; + + if (left->oid[2] == right->oid[2]) { + if (left->oid[1] == right->oid[1]) { + if (left->oid[0] == right->oid[0]) + ret = 0; + else if (left->oid[0] < right->oid[0]) + ret = -1; + else + return 1; + } else if (left->oid[1] < right->oid[1]) + ret = -1; + else + ret = 1; + } else if (left->oid[2] < right->oid[2]) + ret = -1; + else + ret = 1; + return ret; +} + +static inline unsigned tmem_oid_hash(struct tmem_oid *oidp) +{ + return hash_long(oidp->oid[0] ^ oidp->oid[1] ^ oidp->oid[2], + TMEM_HASH_BUCKET_BITS); +} + +/* + * A tmem_obj contains an identifier (oid), pointers to the parent + * pool and the rb_tree to which it belongs, counters, and an ordered + * set of pampds, structured in a radix-tree-like tree. The intermediate + * nodes of the tree are called tmem_objnodes. + */ + +struct tmem_objnode; + +struct tmem_obj { + struct tmem_oid oid; + struct tmem_pool *pool; + struct rb_node rb_tree_node; + struct tmem_objnode *objnode_tree_root; + unsigned int objnode_tree_height; + unsigned long objnode_count; + long pampd_count; + void *extra; /* for private use by pampd implementation */ + DECL_SENTINEL +}; + +#define OBJNODE_TREE_MAP_SHIFT 6 +#define OBJNODE_TREE_MAP_SIZE (1UL << OBJNODE_TREE_MAP_SHIFT) +#define OBJNODE_TREE_MAP_MASK (OBJNODE_TREE_MAP_SIZE-1) +#define OBJNODE_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) +#define OBJNODE_TREE_MAX_PATH \ + (OBJNODE_TREE_INDEX_BITS/OBJNODE_TREE_MAP_SHIFT + 2) + +struct tmem_objnode { + struct tmem_obj *obj; + DECL_SENTINEL + void *slots[OBJNODE_TREE_MAP_SIZE]; + unsigned int slots_in_use; +}; + +/* pampd abstract datatype methods provided by the PAM implementation */ +struct tmem_pamops { + void *(*create)(char *, size_t, bool, int, + struct tmem_pool *, struct tmem_oid *, uint32_t); + int (*get_data)(char *, size_t *, bool, void *, struct tmem_pool *, + struct tmem_oid *, uint32_t); + int (*get_data_and_free)(char *, size_t *, bool, void *, + struct tmem_pool *, struct tmem_oid *, + uint32_t); + void (*free)(void *, struct tmem_pool *, struct tmem_oid *, uint32_t); + void (*free_obj)(struct tmem_pool *, struct tmem_obj *); + bool (*is_remote)(void *); + void (*new_obj)(struct tmem_obj *); + int (*replace_in_obj)(void *, struct tmem_obj *); +}; +extern void tmem_register_pamops(struct tmem_pamops *m); + +/* memory allocation methods provided by the host implementation */ +struct tmem_hostops { + struct tmem_obj *(*obj_alloc)(struct tmem_pool *); + void (*obj_free)(struct tmem_obj *, struct tmem_pool *); + struct tmem_objnode *(*objnode_alloc)(struct tmem_pool *); + void (*objnode_free)(struct tmem_objnode *, struct tmem_pool *); +}; +extern void tmem_register_hostops(struct tmem_hostops *m); + +/* core tmem accessor functions */ +extern int tmem_put(struct tmem_pool *, struct tmem_oid *, uint32_t index, + char *, size_t, bool, bool); +extern int tmem_get(struct tmem_pool *, struct tmem_oid *, uint32_t index, + char *, size_t *, bool, int); +extern int tmem_replace(struct tmem_pool *, struct tmem_oid *, uint32_t index, + void *); +extern int tmem_flush_page(struct tmem_pool *, struct tmem_oid *, + uint32_t index); +extern int tmem_flush_object(struct tmem_pool *, struct tmem_oid *); +extern int tmem_destroy_pool(struct tmem_pool *); +extern void tmem_new_pool(struct tmem_pool *, uint32_t); +#endif /* _TMEM_H */ diff --git a/drivers/staging/ramster/zcache-main.c b/drivers/staging/ramster/zcache-main.c new file mode 100644 index 0000000..49c8791 --- /dev/null +++ b/drivers/staging/ramster/zcache-main.c @@ -0,0 +1,1988 @@ +/* + * zcache.c + * + * Copyright (c) 2010,2011, Dan Magenheimer, Oracle Corp. + * Copyright (c) 2010,2011, Nitin Gupta + * + * Zcache provides an in-kernel "host implementation" for transcendent memory + * and, thus indirectly, for cleancache and frontswap. Zcache includes two + * page-accessible memory [1] interfaces, both utilizing lzo1x compression: + * 1) "compression buddies" ("zbud") is used for ephemeral pages + * 2) xvmalloc is used for persistent pages. + * Xvmalloc (based on the TLSF allocator) has very low fragmentation + * so maximizes space efficiency, while zbud allows pairs (and potentially, + * in the future, more than a pair of) compressed pages to be closely linked + * so that reclaiming can be done via the kernel's physical-page-oriented + * "shrinker" interface. + * + * [1] For a definition of page-accessible memory (aka PAM), see: + * http://marc.info/?l=linux-mm&m=127811271605009 + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "tmem.h" + +#include "../zram/xvmalloc.h" /* if built in drivers/staging */ + +#if (!defined(CONFIG_CLEANCACHE) && !defined(CONFIG_FRONTSWAP)) +#error "zcache is useless without CONFIG_CLEANCACHE or CONFIG_FRONTSWAP" +#endif +#ifdef CONFIG_CLEANCACHE +#include +#endif +#ifdef CONFIG_FRONTSWAP +#include +#endif + +#if 0 +/* this is more aggressive but may cause other problems? */ +#define ZCACHE_GFP_MASK (GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN) +#else +#define ZCACHE_GFP_MASK \ + (__GFP_FS | __GFP_NORETRY | __GFP_NOWARN | __GFP_NOMEMALLOC) +#endif + +#define MAX_POOLS_PER_CLIENT 16 + +#define MAX_CLIENTS 16 +#define LOCAL_CLIENT ((uint16_t)-1) + +MODULE_LICENSE("GPL"); + +struct zcache_client { + struct tmem_pool *tmem_pools[MAX_POOLS_PER_CLIENT]; + struct xv_pool *xvpool; + bool allocated; + atomic_t refcount; +}; + +static struct zcache_client zcache_host; +static struct zcache_client zcache_clients[MAX_CLIENTS]; + +static inline uint16_t get_client_id_from_client(struct zcache_client *cli) +{ + BUG_ON(cli == NULL); + if (cli == &zcache_host) + return LOCAL_CLIENT; + return cli - &zcache_clients[0]; +} + +static inline bool is_local_client(struct zcache_client *cli) +{ + return cli == &zcache_host; +} + +/********** + * Compression buddies ("zbud") provides for packing two (or, possibly + * in the future, more) compressed ephemeral pages into a single "raw" + * (physical) page and tracking them with data structures so that + * the raw pages can be easily reclaimed. + * + * A zbud page ("zbpg") is an aligned page containing a list_head, + * a lock, and two "zbud headers". The remainder of the physical + * page is divided up into aligned 64-byte "chunks" which contain + * the compressed data for zero, one, or two zbuds. Each zbpg + * resides on: (1) an "unused list" if it has no zbuds; (2) a + * "buddied" list if it is fully populated with two zbuds; or + * (3) one of PAGE_SIZE/64 "unbuddied" lists indexed by how many chunks + * the one unbuddied zbud uses. The data inside a zbpg cannot be + * read or written unless the zbpg's lock is held. + */ + +#define ZBH_SENTINEL 0x43214321 +#define ZBPG_SENTINEL 0xdeadbeef + +#define ZBUD_MAX_BUDS 2 + +struct zbud_hdr { + uint16_t client_id; + uint16_t pool_id; + struct tmem_oid oid; + uint32_t index; + uint16_t size; /* compressed size in bytes, zero means unused */ + DECL_SENTINEL +}; + +struct zbud_page { + struct list_head bud_list; + spinlock_t lock; + struct zbud_hdr buddy[ZBUD_MAX_BUDS]; + DECL_SENTINEL + /* followed by NUM_CHUNK aligned CHUNK_SIZE-byte chunks */ +}; + +#define CHUNK_SHIFT 6 +#define CHUNK_SIZE (1 << CHUNK_SHIFT) +#define CHUNK_MASK (~(CHUNK_SIZE-1)) +#define NCHUNKS (((PAGE_SIZE - sizeof(struct zbud_page)) & \ + CHUNK_MASK) >> CHUNK_SHIFT) +#define MAX_CHUNK (NCHUNKS-1) + +static struct { + struct list_head list; + unsigned count; +} zbud_unbuddied[NCHUNKS]; +/* list N contains pages with N chunks USED and NCHUNKS-N unused */ +/* element 0 is never used but optimizing that isn't worth it */ +static unsigned long zbud_cumul_chunk_counts[NCHUNKS]; + +struct list_head zbud_buddied_list; +static unsigned long zcache_zbud_buddied_count; + +/* protects the buddied list and all unbuddied lists */ +static DEFINE_SPINLOCK(zbud_budlists_spinlock); + +static LIST_HEAD(zbpg_unused_list); +static unsigned long zcache_zbpg_unused_list_count; + +/* protects the unused page list */ +static DEFINE_SPINLOCK(zbpg_unused_list_spinlock); + +static atomic_t zcache_zbud_curr_raw_pages; +static atomic_t zcache_zbud_curr_zpages; +static unsigned long zcache_zbud_curr_zbytes; +static unsigned long zcache_zbud_cumul_zpages; +static unsigned long zcache_zbud_cumul_zbytes; +static unsigned long zcache_compress_poor; +static unsigned long zcache_mean_compress_poor; + +/* forward references */ +static void *zcache_get_free_page(void); +static void zcache_free_page(void *p); + +/* + * zbud helper functions + */ + +static inline unsigned zbud_max_buddy_size(void) +{ + return MAX_CHUNK << CHUNK_SHIFT; +} + +static inline unsigned zbud_size_to_chunks(unsigned size) +{ + BUG_ON(size == 0 || size > zbud_max_buddy_size()); + return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT; +} + +static inline int zbud_budnum(struct zbud_hdr *zh) +{ + unsigned offset = (unsigned long)zh & (PAGE_SIZE - 1); + struct zbud_page *zbpg = NULL; + unsigned budnum = -1U; + int i; + + for (i = 0; i < ZBUD_MAX_BUDS; i++) + if (offset == offsetof(typeof(*zbpg), buddy[i])) { + budnum = i; + break; + } + BUG_ON(budnum == -1U); + return budnum; +} + +static char *zbud_data(struct zbud_hdr *zh, unsigned size) +{ + struct zbud_page *zbpg; + char *p; + unsigned budnum; + + ASSERT_SENTINEL(zh, ZBH); + budnum = zbud_budnum(zh); + BUG_ON(size == 0 || size > zbud_max_buddy_size()); + zbpg = container_of(zh, struct zbud_page, buddy[budnum]); + ASSERT_SPINLOCK(&zbpg->lock); + p = (char *)zbpg; + if (budnum == 0) + p += ((sizeof(struct zbud_page) + CHUNK_SIZE - 1) & + CHUNK_MASK); + else if (budnum == 1) + p += PAGE_SIZE - ((size + CHUNK_SIZE - 1) & CHUNK_MASK); + return p; +} + +/* + * zbud raw page management + */ + +static struct zbud_page *zbud_alloc_raw_page(void) +{ + struct zbud_page *zbpg = NULL; + struct zbud_hdr *zh0, *zh1; + bool recycled = 0; + + /* if any pages on the zbpg list, use one */ + spin_lock(&zbpg_unused_list_spinlock); + if (!list_empty(&zbpg_unused_list)) { + zbpg = list_first_entry(&zbpg_unused_list, + struct zbud_page, bud_list); + list_del_init(&zbpg->bud_list); + zcache_zbpg_unused_list_count--; + recycled = 1; + } + spin_unlock(&zbpg_unused_list_spinlock); + if (zbpg == NULL) + /* none on zbpg list, try to get a kernel page */ + zbpg = zcache_get_free_page(); + if (likely(zbpg != NULL)) { + INIT_LIST_HEAD(&zbpg->bud_list); + zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1]; + spin_lock_init(&zbpg->lock); + if (recycled) { + ASSERT_INVERTED_SENTINEL(zbpg, ZBPG); + SET_SENTINEL(zbpg, ZBPG); + BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid)); + BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid)); + } else { + atomic_inc(&zcache_zbud_curr_raw_pages); + INIT_LIST_HEAD(&zbpg->bud_list); + SET_SENTINEL(zbpg, ZBPG); + zh0->size = 0; zh1->size = 0; + tmem_oid_set_invalid(&zh0->oid); + tmem_oid_set_invalid(&zh1->oid); + } + } + return zbpg; +} + +static void zbud_free_raw_page(struct zbud_page *zbpg) +{ + struct zbud_hdr *zh0 = &zbpg->buddy[0], *zh1 = &zbpg->buddy[1]; + + ASSERT_SENTINEL(zbpg, ZBPG); + BUG_ON(!list_empty(&zbpg->bud_list)); + ASSERT_SPINLOCK(&zbpg->lock); + BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid)); + BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid)); + INVERT_SENTINEL(zbpg, ZBPG); + spin_unlock(&zbpg->lock); + spin_lock(&zbpg_unused_list_spinlock); + list_add(&zbpg->bud_list, &zbpg_unused_list); + zcache_zbpg_unused_list_count++; + spin_unlock(&zbpg_unused_list_spinlock); +} + +/* + * core zbud handling routines + */ + +static unsigned zbud_free(struct zbud_hdr *zh) +{ + unsigned size; + + ASSERT_SENTINEL(zh, ZBH); + BUG_ON(!tmem_oid_valid(&zh->oid)); + size = zh->size; + BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size()); + zh->size = 0; + tmem_oid_set_invalid(&zh->oid); + INVERT_SENTINEL(zh, ZBH); + zcache_zbud_curr_zbytes -= size; + atomic_dec(&zcache_zbud_curr_zpages); + return size; +} + +static void zbud_free_and_delist(struct zbud_hdr *zh) +{ + unsigned chunks; + struct zbud_hdr *zh_other; + unsigned budnum = zbud_budnum(zh), size; + struct zbud_page *zbpg = + container_of(zh, struct zbud_page, buddy[budnum]); + + spin_lock(&zbpg->lock); + if (list_empty(&zbpg->bud_list)) { + /* ignore zombie page... see zbud_evict_pages() */ + spin_unlock(&zbpg->lock); + return; + } + size = zbud_free(zh); + ASSERT_SPINLOCK(&zbpg->lock); + zh_other = &zbpg->buddy[(budnum == 0) ? 1 : 0]; + if (zh_other->size == 0) { /* was unbuddied: unlist and free */ + chunks = zbud_size_to_chunks(size) ; + spin_lock(&zbud_budlists_spinlock); + BUG_ON(list_empty(&zbud_unbuddied[chunks].list)); + list_del_init(&zbpg->bud_list); + zbud_unbuddied[chunks].count--; + spin_unlock(&zbud_budlists_spinlock); + zbud_free_raw_page(zbpg); + } else { /* was buddied: move remaining buddy to unbuddied list */ + chunks = zbud_size_to_chunks(zh_other->size) ; + spin_lock(&zbud_budlists_spinlock); + list_del_init(&zbpg->bud_list); + zcache_zbud_buddied_count--; + list_add_tail(&zbpg->bud_list, &zbud_unbuddied[chunks].list); + zbud_unbuddied[chunks].count++; + spin_unlock(&zbud_budlists_spinlock); + spin_unlock(&zbpg->lock); + } +} + +static struct zbud_hdr *zbud_create(uint16_t client_id, uint16_t pool_id, + struct tmem_oid *oid, + uint32_t index, struct page *page, + void *cdata, unsigned size) +{ + struct zbud_hdr *zh0, *zh1, *zh = NULL; + struct zbud_page *zbpg = NULL, *ztmp; + unsigned nchunks; + char *to; + int i, found_good_buddy = 0; + + nchunks = zbud_size_to_chunks(size) ; + for (i = MAX_CHUNK - nchunks + 1; i > 0; i--) { + spin_lock(&zbud_budlists_spinlock); + if (!list_empty(&zbud_unbuddied[i].list)) { + list_for_each_entry_safe(zbpg, ztmp, + &zbud_unbuddied[i].list, bud_list) { + if (spin_trylock(&zbpg->lock)) { + found_good_buddy = i; + goto found_unbuddied; + } + } + } + spin_unlock(&zbud_budlists_spinlock); + } + /* didn't find a good buddy, try allocating a new page */ + zbpg = zbud_alloc_raw_page(); + if (unlikely(zbpg == NULL)) + goto out; + /* ok, have a page, now compress the data before taking locks */ + spin_lock(&zbpg->lock); + spin_lock(&zbud_budlists_spinlock); + list_add_tail(&zbpg->bud_list, &zbud_unbuddied[nchunks].list); + zbud_unbuddied[nchunks].count++; + zh = &zbpg->buddy[0]; + goto init_zh; + +found_unbuddied: + ASSERT_SPINLOCK(&zbpg->lock); + zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1]; + BUG_ON(!((zh0->size == 0) ^ (zh1->size == 0))); + if (zh0->size != 0) { /* buddy0 in use, buddy1 is vacant */ + ASSERT_SENTINEL(zh0, ZBH); + zh = zh1; + } else if (zh1->size != 0) { /* buddy1 in use, buddy0 is vacant */ + ASSERT_SENTINEL(zh1, ZBH); + zh = zh0; + } else + BUG(); + list_del_init(&zbpg->bud_list); + zbud_unbuddied[found_good_buddy].count--; + list_add_tail(&zbpg->bud_list, &zbud_buddied_list); + zcache_zbud_buddied_count++; + +init_zh: + SET_SENTINEL(zh, ZBH); + zh->size = size; + zh->index = index; + zh->oid = *oid; + zh->pool_id = pool_id; + zh->client_id = client_id; + /* can wait to copy the data until the list locks are dropped */ + spin_unlock(&zbud_budlists_spinlock); + + to = zbud_data(zh, size); + memcpy(to, cdata, size); + spin_unlock(&zbpg->lock); + zbud_cumul_chunk_counts[nchunks]++; + atomic_inc(&zcache_zbud_curr_zpages); + zcache_zbud_cumul_zpages++; + zcache_zbud_curr_zbytes += size; + zcache_zbud_cumul_zbytes += size; +out: + return zh; +} + +static int zbud_decompress(struct page *page, struct zbud_hdr *zh) +{ + struct zbud_page *zbpg; + unsigned budnum = zbud_budnum(zh); + size_t out_len = PAGE_SIZE; + char *to_va, *from_va; + unsigned size; + int ret = 0; + + zbpg = container_of(zh, struct zbud_page, buddy[budnum]); + spin_lock(&zbpg->lock); + if (list_empty(&zbpg->bud_list)) { + /* ignore zombie page... see zbud_evict_pages() */ + ret = -EINVAL; + goto out; + } + ASSERT_SENTINEL(zh, ZBH); + BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size()); + to_va = kmap_atomic(page, KM_USER0); + size = zh->size; + from_va = zbud_data(zh, size); + ret = lzo1x_decompress_safe(from_va, size, to_va, &out_len); + BUG_ON(ret != LZO_E_OK); + BUG_ON(out_len != PAGE_SIZE); + kunmap_atomic(to_va, KM_USER0); +out: + spin_unlock(&zbpg->lock); + return ret; +} + +/* + * The following routines handle shrinking of ephemeral pages by evicting + * pages "least valuable" first. + */ + +static unsigned long zcache_evicted_raw_pages; +static unsigned long zcache_evicted_buddied_pages; +static unsigned long zcache_evicted_unbuddied_pages; + +static struct tmem_pool *zcache_get_pool_by_id(uint16_t cli_id, + uint16_t poolid); +static void zcache_put_pool(struct tmem_pool *pool); + +/* + * Flush and free all zbuds in a zbpg, then free the pageframe + */ +static void zbud_evict_zbpg(struct zbud_page *zbpg) +{ + struct zbud_hdr *zh; + int i, j; + uint32_t pool_id[ZBUD_MAX_BUDS], client_id[ZBUD_MAX_BUDS]; + uint32_t index[ZBUD_MAX_BUDS]; + struct tmem_oid oid[ZBUD_MAX_BUDS]; + struct tmem_pool *pool; + + ASSERT_SPINLOCK(&zbpg->lock); + BUG_ON(!list_empty(&zbpg->bud_list)); + for (i = 0, j = 0; i < ZBUD_MAX_BUDS; i++) { + zh = &zbpg->buddy[i]; + if (zh->size) { + client_id[j] = zh->client_id; + pool_id[j] = zh->pool_id; + oid[j] = zh->oid; + index[j] = zh->index; + j++; + zbud_free(zh); + } + } + spin_unlock(&zbpg->lock); + for (i = 0; i < j; i++) { + pool = zcache_get_pool_by_id(client_id[i], pool_id[i]); + if (pool != NULL) { + tmem_flush_page(pool, &oid[i], index[i]); + zcache_put_pool(pool); + } + } + ASSERT_SENTINEL(zbpg, ZBPG); + spin_lock(&zbpg->lock); + zbud_free_raw_page(zbpg); +} + +/* + * Free nr pages. This code is funky because we want to hold the locks + * protecting various lists for as short a time as possible, and in some + * circumstances the list may change asynchronously when the list lock is + * not held. In some cases we also trylock not only to avoid waiting on a + * page in use by another cpu, but also to avoid potential deadlock due to + * lock inversion. + */ +static void zbud_evict_pages(int nr) +{ + struct zbud_page *zbpg; + int i; + + /* first try freeing any pages on unused list */ +retry_unused_list: + spin_lock_bh(&zbpg_unused_list_spinlock); + if (!list_empty(&zbpg_unused_list)) { + /* can't walk list here, since it may change when unlocked */ + zbpg = list_first_entry(&zbpg_unused_list, + struct zbud_page, bud_list); + list_del_init(&zbpg->bud_list); + zcache_zbpg_unused_list_count--; + atomic_dec(&zcache_zbud_curr_raw_pages); + spin_unlock_bh(&zbpg_unused_list_spinlock); + zcache_free_page(zbpg); + zcache_evicted_raw_pages++; + if (--nr <= 0) + goto out; + goto retry_unused_list; + } + spin_unlock_bh(&zbpg_unused_list_spinlock); + + /* now try freeing unbuddied pages, starting with least space avail */ + for (i = 0; i < MAX_CHUNK; i++) { +retry_unbud_list_i: + spin_lock_bh(&zbud_budlists_spinlock); + if (list_empty(&zbud_unbuddied[i].list)) { + spin_unlock_bh(&zbud_budlists_spinlock); + continue; + } + list_for_each_entry(zbpg, &zbud_unbuddied[i].list, bud_list) { + if (unlikely(!spin_trylock(&zbpg->lock))) + continue; + list_del_init(&zbpg->bud_list); + zbud_unbuddied[i].count--; + spin_unlock(&zbud_budlists_spinlock); + zcache_evicted_unbuddied_pages++; + /* want budlists unlocked when doing zbpg eviction */ + zbud_evict_zbpg(zbpg); + local_bh_enable(); + if (--nr <= 0) + goto out; + goto retry_unbud_list_i; + } + spin_unlock_bh(&zbud_budlists_spinlock); + } + + /* as a last resort, free buddied pages */ +retry_bud_list: + spin_lock_bh(&zbud_budlists_spinlock); + if (list_empty(&zbud_buddied_list)) { + spin_unlock_bh(&zbud_budlists_spinlock); + goto out; + } + list_for_each_entry(zbpg, &zbud_buddied_list, bud_list) { + if (unlikely(!spin_trylock(&zbpg->lock))) + continue; + list_del_init(&zbpg->bud_list); + zcache_zbud_buddied_count--; + spin_unlock(&zbud_budlists_spinlock); + zcache_evicted_buddied_pages++; + /* want budlists unlocked when doing zbpg eviction */ + zbud_evict_zbpg(zbpg); + local_bh_enable(); + if (--nr <= 0) + goto out; + goto retry_bud_list; + } + spin_unlock_bh(&zbud_budlists_spinlock); +out: + return; +} + +static void zbud_init(void) +{ + int i; + + INIT_LIST_HEAD(&zbud_buddied_list); + zcache_zbud_buddied_count = 0; + for (i = 0; i < NCHUNKS; i++) { + INIT_LIST_HEAD(&zbud_unbuddied[i].list); + zbud_unbuddied[i].count = 0; + } +} + +#ifdef CONFIG_SYSFS +/* + * These sysfs routines show a nice distribution of how many zbpg's are + * currently (and have ever been placed) in each unbuddied list. It's fun + * to watch but can probably go away before final merge. + */ +static int zbud_show_unbuddied_list_counts(char *buf) +{ + int i; + char *p = buf; + + for (i = 0; i < NCHUNKS; i++) + p += sprintf(p, "%u ", zbud_unbuddied[i].count); + return p - buf; +} + +static int zbud_show_cumul_chunk_counts(char *buf) +{ + unsigned long i, chunks = 0, total_chunks = 0, sum_total_chunks = 0; + unsigned long total_chunks_lte_21 = 0, total_chunks_lte_32 = 0; + unsigned long total_chunks_lte_42 = 0; + char *p = buf; + + for (i = 0; i < NCHUNKS; i++) { + p += sprintf(p, "%lu ", zbud_cumul_chunk_counts[i]); + chunks += zbud_cumul_chunk_counts[i]; + total_chunks += zbud_cumul_chunk_counts[i]; + sum_total_chunks += i * zbud_cumul_chunk_counts[i]; + if (i == 21) + total_chunks_lte_21 = total_chunks; + if (i == 32) + total_chunks_lte_32 = total_chunks; + if (i == 42) + total_chunks_lte_42 = total_chunks; + } + p += sprintf(p, "<=21:%lu <=32:%lu <=42:%lu, mean:%lu\n", + total_chunks_lte_21, total_chunks_lte_32, total_chunks_lte_42, + chunks == 0 ? 0 : sum_total_chunks / chunks); + return p - buf; +} +#endif + +/********** + * This "zv" PAM implementation combines the TLSF-based xvMalloc + * with lzo1x compression to maximize the amount of data that can + * be packed into a physical page. + * + * Zv represents a PAM page with the index and object (plus a "size" value + * necessary for decompression) immediately preceding the compressed data. + */ + +#define ZVH_SENTINEL 0x43214321 + +struct zv_hdr { + uint32_t pool_id; + struct tmem_oid oid; + uint32_t index; + DECL_SENTINEL +}; + +/* rudimentary policy limits */ +/* total number of persistent pages may not exceed this percentage */ +static unsigned int zv_page_count_policy_percent = 75; +/* + * byte count defining poor compression; pages with greater zsize will be + * rejected + */ +static unsigned int zv_max_zsize = (PAGE_SIZE / 8) * 7; +/* + * byte count defining poor *mean* compression; pages with greater zsize + * will be rejected until sufficient better-compressed pages are accepted + * driving the mean below this threshold + */ +static unsigned int zv_max_mean_zsize = (PAGE_SIZE / 8) * 5; + +static unsigned long zv_curr_dist_counts[NCHUNKS]; +static unsigned long zv_cumul_dist_counts[NCHUNKS]; + +static struct zv_hdr *zv_create(struct xv_pool *xvpool, uint32_t pool_id, + struct tmem_oid *oid, uint32_t index, + void *cdata, unsigned clen) +{ + struct page *page; + struct zv_hdr *zv = NULL; + uint32_t offset; + int alloc_size = clen + sizeof(struct zv_hdr); + int chunks = (alloc_size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT; + int ret; + + BUG_ON(!irqs_disabled()); + BUG_ON(chunks >= NCHUNKS); + ret = xv_malloc(xvpool, alloc_size, + &page, &offset, ZCACHE_GFP_MASK); + if (unlikely(ret)) + goto out; + zv_curr_dist_counts[chunks]++; + zv_cumul_dist_counts[chunks]++; + zv = kmap_atomic(page, KM_USER0) + offset; + zv->index = index; + zv->oid = *oid; + zv->pool_id = pool_id; + SET_SENTINEL(zv, ZVH); + memcpy((char *)zv + sizeof(struct zv_hdr), cdata, clen); + kunmap_atomic(zv, KM_USER0); +out: + return zv; +} + +static void zv_free(struct xv_pool *xvpool, struct zv_hdr *zv) +{ + unsigned long flags; + struct page *page; + uint32_t offset; + uint16_t size = xv_get_object_size(zv); + int chunks = (size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT; + + ASSERT_SENTINEL(zv, ZVH); + BUG_ON(chunks >= NCHUNKS); + zv_curr_dist_counts[chunks]--; + size -= sizeof(*zv); + BUG_ON(size == 0); + INVERT_SENTINEL(zv, ZVH); + page = virt_to_page(zv); + offset = (unsigned long)zv & ~PAGE_MASK; + local_irq_save(flags); + xv_free(xvpool, page, offset); + local_irq_restore(flags); +} + +static void zv_decompress(struct page *page, struct zv_hdr *zv) +{ + size_t clen = PAGE_SIZE; + char *to_va; + unsigned size; + int ret; + + ASSERT_SENTINEL(zv, ZVH); + size = xv_get_object_size(zv) - sizeof(*zv); + BUG_ON(size == 0); + to_va = kmap_atomic(page, KM_USER0); + ret = lzo1x_decompress_safe((char *)zv + sizeof(*zv), + size, to_va, &clen); + kunmap_atomic(to_va, KM_USER0); + BUG_ON(ret != LZO_E_OK); + BUG_ON(clen != PAGE_SIZE); +} + +#ifdef CONFIG_SYSFS +/* + * show a distribution of compression stats for zv pages. + */ + +static int zv_curr_dist_counts_show(char *buf) +{ + unsigned long i, n, chunks = 0, sum_total_chunks = 0; + char *p = buf; + + for (i = 0; i < NCHUNKS; i++) { + n = zv_curr_dist_counts[i]; + p += sprintf(p, "%lu ", n); + chunks += n; + sum_total_chunks += i * n; + } + p += sprintf(p, "mean:%lu\n", + chunks == 0 ? 0 : sum_total_chunks / chunks); + return p - buf; +} + +static int zv_cumul_dist_counts_show(char *buf) +{ + unsigned long i, n, chunks = 0, sum_total_chunks = 0; + char *p = buf; + + for (i = 0; i < NCHUNKS; i++) { + n = zv_cumul_dist_counts[i]; + p += sprintf(p, "%lu ", n); + chunks += n; + sum_total_chunks += i * n; + } + p += sprintf(p, "mean:%lu\n", + chunks == 0 ? 0 : sum_total_chunks / chunks); + return p - buf; +} + +/* + * setting zv_max_zsize via sysfs causes all persistent (e.g. swap) + * pages that don't compress to less than this value (including metadata + * overhead) to be rejected. We don't allow the value to get too close + * to PAGE_SIZE. + */ +static ssize_t zv_max_zsize_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *buf) +{ + return sprintf(buf, "%u\n", zv_max_zsize); +} + +static ssize_t zv_max_zsize_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + unsigned long val; + int err; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + err = strict_strtoul(buf, 10, &val); + if (err || (val == 0) || (val > (PAGE_SIZE / 8) * 7)) + return -EINVAL; + zv_max_zsize = val; + return count; +} + +/* + * setting zv_max_mean_zsize via sysfs causes all persistent (e.g. swap) + * pages that don't compress to less than this value (including metadata + * overhead) to be rejected UNLESS the mean compression is also smaller + * than this value. In other words, we are load-balancing-by-zsize the + * accepted pages. Again, we don't allow the value to get too close + * to PAGE_SIZE. + */ +static ssize_t zv_max_mean_zsize_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *buf) +{ + return sprintf(buf, "%u\n", zv_max_mean_zsize); +} + +static ssize_t zv_max_mean_zsize_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + unsigned long val; + int err; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + err = strict_strtoul(buf, 10, &val); + if (err || (val == 0) || (val > (PAGE_SIZE / 8) * 7)) + return -EINVAL; + zv_max_mean_zsize = val; + return count; +} + +/* + * setting zv_page_count_policy_percent via sysfs sets an upper bound of + * persistent (e.g. swap) pages that will be retained according to: + * (zv_page_count_policy_percent * totalram_pages) / 100) + * when that limit is reached, further puts will be rejected (until + * some pages have been flushed). Note that, due to compression, + * this number may exceed 100; it defaults to 75 and we set an + * arbitary limit of 150. A poor choice will almost certainly result + * in OOM's, so this value should only be changed prudently. + */ +static ssize_t zv_page_count_policy_percent_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *buf) +{ + return sprintf(buf, "%u\n", zv_page_count_policy_percent); +} + +static ssize_t zv_page_count_policy_percent_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + unsigned long val; + int err; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + err = strict_strtoul(buf, 10, &val); + if (err || (val == 0) || (val > 150)) + return -EINVAL; + zv_page_count_policy_percent = val; + return count; +} + +static struct kobj_attribute zcache_zv_max_zsize_attr = { + .attr = { .name = "zv_max_zsize", .mode = 0644 }, + .show = zv_max_zsize_show, + .store = zv_max_zsize_store, +}; + +static struct kobj_attribute zcache_zv_max_mean_zsize_attr = { + .attr = { .name = "zv_max_mean_zsize", .mode = 0644 }, + .show = zv_max_mean_zsize_show, + .store = zv_max_mean_zsize_store, +}; + +static struct kobj_attribute zcache_zv_page_count_policy_percent_attr = { + .attr = { .name = "zv_page_count_policy_percent", + .mode = 0644 }, + .show = zv_page_count_policy_percent_show, + .store = zv_page_count_policy_percent_store, +}; +#endif + +/* + * zcache core code starts here + */ + +/* useful stats not collected by cleancache or frontswap */ +static unsigned long zcache_flush_total; +static unsigned long zcache_flush_found; +static unsigned long zcache_flobj_total; +static unsigned long zcache_flobj_found; +static unsigned long zcache_failed_eph_puts; +static unsigned long zcache_failed_pers_puts; + +/* + * Tmem operations assume the poolid implies the invoking client. + * Zcache only has one client (the kernel itself): LOCAL_CLIENT. + * RAMster has each client numbered by cluster node, and a KVM version + * of zcache would have one client per guest and each client might + * have a poolid==N. + */ +static struct tmem_pool *zcache_get_pool_by_id(uint16_t cli_id, uint16_t poolid) +{ + struct tmem_pool *pool = NULL; + struct zcache_client *cli = NULL; + + if (cli_id == LOCAL_CLIENT) + cli = &zcache_host; + else { + if (cli_id >= MAX_CLIENTS) + goto out; + cli = &zcache_clients[cli_id]; + if (cli == NULL) + goto out; + atomic_inc(&cli->refcount); + } + if (poolid < MAX_POOLS_PER_CLIENT) { + pool = cli->tmem_pools[poolid]; + if (pool != NULL) + atomic_inc(&pool->refcount); + } +out: + return pool; +} + +static void zcache_put_pool(struct tmem_pool *pool) +{ + struct zcache_client *cli = NULL; + + if (pool == NULL) + BUG(); + cli = pool->client; + atomic_dec(&pool->refcount); + atomic_dec(&cli->refcount); +} + +int zcache_new_client(uint16_t cli_id) +{ + struct zcache_client *cli = NULL; + int ret = -1; + + if (cli_id == LOCAL_CLIENT) + cli = &zcache_host; + else if ((unsigned int)cli_id < MAX_CLIENTS) + cli = &zcache_clients[cli_id]; + if (cli == NULL) + goto out; + if (cli->allocated) + goto out; + cli->allocated = 1; +#ifdef CONFIG_FRONTSWAP + cli->xvpool = xv_create_pool(); + if (cli->xvpool == NULL) + goto out; +#endif + ret = 0; +out: + return ret; +} + +/* counters for debugging */ +static unsigned long zcache_failed_get_free_pages; +static unsigned long zcache_failed_alloc; +static unsigned long zcache_put_to_flush; + +/* + * for now, used named slabs so can easily track usage; later can + * either just use kmalloc, or perhaps add a slab-like allocator + * to more carefully manage total memory utilization + */ +static struct kmem_cache *zcache_objnode_cache; +static struct kmem_cache *zcache_obj_cache; +static atomic_t zcache_curr_obj_count = ATOMIC_INIT(0); +static unsigned long zcache_curr_obj_count_max; +static atomic_t zcache_curr_objnode_count = ATOMIC_INIT(0); +static unsigned long zcache_curr_objnode_count_max; + +/* + * to avoid memory allocation recursion (e.g. due to direct reclaim), we + * preload all necessary data structures so the hostops callbacks never + * actually do a malloc + */ +struct zcache_preload { + void *page; + struct tmem_obj *obj; + int nr; + struct tmem_objnode *objnodes[OBJNODE_TREE_MAX_PATH]; +}; +static DEFINE_PER_CPU(struct zcache_preload, zcache_preloads) = { 0, }; + +static int zcache_do_preload(struct tmem_pool *pool) +{ + struct zcache_preload *kp; + struct tmem_objnode *objnode; + struct tmem_obj *obj; + void *page; + int ret = -ENOMEM; + + if (unlikely(zcache_objnode_cache == NULL)) + goto out; + if (unlikely(zcache_obj_cache == NULL)) + goto out; + preempt_disable(); + kp = &__get_cpu_var(zcache_preloads); + while (kp->nr < ARRAY_SIZE(kp->objnodes)) { + preempt_enable_no_resched(); + objnode = kmem_cache_alloc(zcache_objnode_cache, + ZCACHE_GFP_MASK); + if (unlikely(objnode == NULL)) { + zcache_failed_alloc++; + goto out; + } + preempt_disable(); + kp = &__get_cpu_var(zcache_preloads); + if (kp->nr < ARRAY_SIZE(kp->objnodes)) + kp->objnodes[kp->nr++] = objnode; + else + kmem_cache_free(zcache_objnode_cache, objnode); + } + preempt_enable_no_resched(); + obj = kmem_cache_alloc(zcache_obj_cache, ZCACHE_GFP_MASK); + if (unlikely(obj == NULL)) { + zcache_failed_alloc++; + goto out; + } + page = (void *)__get_free_page(ZCACHE_GFP_MASK); + if (unlikely(page == NULL)) { + zcache_failed_get_free_pages++; + kmem_cache_free(zcache_obj_cache, obj); + goto out; + } + preempt_disable(); + kp = &__get_cpu_var(zcache_preloads); + if (kp->obj == NULL) + kp->obj = obj; + else + kmem_cache_free(zcache_obj_cache, obj); + if (kp->page == NULL) + kp->page = page; + else + free_page((unsigned long)page); + ret = 0; +out: + return ret; +} + +static void *zcache_get_free_page(void) +{ + struct zcache_preload *kp; + void *page; + + kp = &__get_cpu_var(zcache_preloads); + page = kp->page; + BUG_ON(page == NULL); + kp->page = NULL; + return page; +} + +static void zcache_free_page(void *p) +{ + free_page((unsigned long)p); +} + +/* + * zcache implementation for tmem host ops + */ + +static struct tmem_objnode *zcache_objnode_alloc(struct tmem_pool *pool) +{ + struct tmem_objnode *objnode = NULL; + unsigned long count; + struct zcache_preload *kp; + + kp = &__get_cpu_var(zcache_preloads); + if (kp->nr <= 0) + goto out; + objnode = kp->objnodes[kp->nr - 1]; + BUG_ON(objnode == NULL); + kp->objnodes[kp->nr - 1] = NULL; + kp->nr--; + count = atomic_inc_return(&zcache_curr_objnode_count); + if (count > zcache_curr_objnode_count_max) + zcache_curr_objnode_count_max = count; +out: + return objnode; +} + +static void zcache_objnode_free(struct tmem_objnode *objnode, + struct tmem_pool *pool) +{ + atomic_dec(&zcache_curr_objnode_count); + BUG_ON(atomic_read(&zcache_curr_objnode_count) < 0); + kmem_cache_free(zcache_objnode_cache, objnode); +} + +static struct tmem_obj *zcache_obj_alloc(struct tmem_pool *pool) +{ + struct tmem_obj *obj = NULL; + unsigned long count; + struct zcache_preload *kp; + + kp = &__get_cpu_var(zcache_preloads); + obj = kp->obj; + BUG_ON(obj == NULL); + kp->obj = NULL; + count = atomic_inc_return(&zcache_curr_obj_count); + if (count > zcache_curr_obj_count_max) + zcache_curr_obj_count_max = count; + return obj; +} + +static void zcache_obj_free(struct tmem_obj *obj, struct tmem_pool *pool) +{ + atomic_dec(&zcache_curr_obj_count); + BUG_ON(atomic_read(&zcache_curr_obj_count) < 0); + kmem_cache_free(zcache_obj_cache, obj); +} + +static struct tmem_hostops zcache_hostops = { + .obj_alloc = zcache_obj_alloc, + .obj_free = zcache_obj_free, + .objnode_alloc = zcache_objnode_alloc, + .objnode_free = zcache_objnode_free, +}; + +/* + * zcache implementations for PAM page descriptor ops + */ + +static atomic_t zcache_curr_eph_pampd_count = ATOMIC_INIT(0); +static unsigned long zcache_curr_eph_pampd_count_max; +static atomic_t zcache_curr_pers_pampd_count = ATOMIC_INIT(0); +static unsigned long zcache_curr_pers_pampd_count_max; + +/* forward reference */ +static int zcache_compress(struct page *from, void **out_va, size_t *out_len); + +static void *zcache_pampd_create(char *data, size_t size, bool raw, int eph, + struct tmem_pool *pool, struct tmem_oid *oid, + uint32_t index) +{ + void *pampd = NULL, *cdata; + size_t clen; + int ret; + unsigned long count; + struct page *page = (struct page *)(data); + struct zcache_client *cli = pool->client; + uint16_t client_id = get_client_id_from_client(cli); + unsigned long zv_mean_zsize; + unsigned long curr_pers_pampd_count; + u64 total_zsize; + + if (eph) { + ret = zcache_compress(page, &cdata, &clen); + if (ret == 0) + goto out; + if (clen == 0 || clen > zbud_max_buddy_size()) { + zcache_compress_poor++; + goto out; + } + pampd = (void *)zbud_create(client_id, pool->pool_id, oid, + index, page, cdata, clen); + if (pampd != NULL) { + count = atomic_inc_return(&zcache_curr_eph_pampd_count); + if (count > zcache_curr_eph_pampd_count_max) + zcache_curr_eph_pampd_count_max = count; + } + } else { + curr_pers_pampd_count = + atomic_read(&zcache_curr_pers_pampd_count); + if (curr_pers_pampd_count > + (zv_page_count_policy_percent * totalram_pages) / 100) + goto out; + ret = zcache_compress(page, &cdata, &clen); + if (ret == 0) + goto out; + /* reject if compression is too poor */ + if (clen > zv_max_zsize) { + zcache_compress_poor++; + goto out; + } + /* reject if mean compression is too poor */ + if ((clen > zv_max_mean_zsize) && (curr_pers_pampd_count > 0)) { + total_zsize = xv_get_total_size_bytes(cli->xvpool); + zv_mean_zsize = div_u64(total_zsize, + curr_pers_pampd_count); + if (zv_mean_zsize > zv_max_mean_zsize) { + zcache_mean_compress_poor++; + goto out; + } + } + pampd = (void *)zv_create(cli->xvpool, pool->pool_id, + oid, index, cdata, clen); + if (pampd == NULL) + goto out; + count = atomic_inc_return(&zcache_curr_pers_pampd_count); + if (count > zcache_curr_pers_pampd_count_max) + zcache_curr_pers_pampd_count_max = count; + } +out: + return pampd; +} + +/* + * fill the pageframe corresponding to the struct page with the data + * from the passed pampd + */ +static int zcache_pampd_get_data(char *data, size_t *bufsize, bool raw, + void *pampd, struct tmem_pool *pool, + struct tmem_oid *oid, uint32_t index) +{ + int ret = 0; + + BUG_ON(is_ephemeral(pool)); + zv_decompress((struct page *)(data), pampd); + return ret; +} + +/* + * fill the pageframe corresponding to the struct page with the data + * from the passed pampd + */ +static int zcache_pampd_get_data_and_free(char *data, size_t *bufsize, bool raw, + void *pampd, struct tmem_pool *pool, + struct tmem_oid *oid, uint32_t index) +{ + int ret = 0; + + BUG_ON(!is_ephemeral(pool)); + zbud_decompress((struct page *)(data), pampd); + zbud_free_and_delist((struct zbud_hdr *)pampd); + atomic_dec(&zcache_curr_eph_pampd_count); + return ret; +} + +/* + * free the pampd and remove it from any zcache lists + * pampd must no longer be pointed to from any tmem data structures! + */ +static void zcache_pampd_free(void *pampd, struct tmem_pool *pool, + struct tmem_oid *oid, uint32_t index) +{ + struct zcache_client *cli = pool->client; + + if (is_ephemeral(pool)) { + zbud_free_and_delist((struct zbud_hdr *)pampd); + atomic_dec(&zcache_curr_eph_pampd_count); + BUG_ON(atomic_read(&zcache_curr_eph_pampd_count) < 0); + } else { + zv_free(cli->xvpool, (struct zv_hdr *)pampd); + atomic_dec(&zcache_curr_pers_pampd_count); + BUG_ON(atomic_read(&zcache_curr_pers_pampd_count) < 0); + } +} + +static void zcache_pampd_free_obj(struct tmem_pool *pool, struct tmem_obj *obj) +{ +} + +static void zcache_pampd_new_obj(struct tmem_obj *obj) +{ +} + +static int zcache_pampd_replace_in_obj(void *pampd, struct tmem_obj *obj) +{ + return -1; +} + +static bool zcache_pampd_is_remote(void *pampd) +{ + return 0; +} + +static struct tmem_pamops zcache_pamops = { + .create = zcache_pampd_create, + .get_data = zcache_pampd_get_data, + .get_data_and_free = zcache_pampd_get_data_and_free, + .free = zcache_pampd_free, + .free_obj = zcache_pampd_free_obj, + .new_obj = zcache_pampd_new_obj, + .replace_in_obj = zcache_pampd_replace_in_obj, + .is_remote = zcache_pampd_is_remote, +}; + +/* + * zcache compression/decompression and related per-cpu stuff + */ + +#define LZO_WORKMEM_BYTES LZO1X_1_MEM_COMPRESS +#define LZO_DSTMEM_PAGE_ORDER 1 +static DEFINE_PER_CPU(unsigned char *, zcache_workmem); +static DEFINE_PER_CPU(unsigned char *, zcache_dstmem); + +static int zcache_compress(struct page *from, void **out_va, size_t *out_len) +{ + int ret = 0; + unsigned char *dmem = __get_cpu_var(zcache_dstmem); + unsigned char *wmem = __get_cpu_var(zcache_workmem); + char *from_va; + + BUG_ON(!irqs_disabled()); + if (unlikely(dmem == NULL || wmem == NULL)) + goto out; /* no buffer, so can't compress */ + from_va = kmap_atomic(from, KM_USER0); + mb(); + ret = lzo1x_1_compress(from_va, PAGE_SIZE, dmem, out_len, wmem); + BUG_ON(ret != LZO_E_OK); + *out_va = dmem; + kunmap_atomic(from_va, KM_USER0); + ret = 1; +out: + return ret; +} + + +static int zcache_cpu_notifier(struct notifier_block *nb, + unsigned long action, void *pcpu) +{ + int cpu = (long)pcpu; + struct zcache_preload *kp; + + switch (action) { + case CPU_UP_PREPARE: + per_cpu(zcache_dstmem, cpu) = (void *)__get_free_pages( + GFP_KERNEL | __GFP_REPEAT, + LZO_DSTMEM_PAGE_ORDER), + per_cpu(zcache_workmem, cpu) = + kzalloc(LZO1X_MEM_COMPRESS, + GFP_KERNEL | __GFP_REPEAT); + break; + case CPU_DEAD: + case CPU_UP_CANCELED: + free_pages((unsigned long)per_cpu(zcache_dstmem, cpu), + LZO_DSTMEM_PAGE_ORDER); + per_cpu(zcache_dstmem, cpu) = NULL; + kfree(per_cpu(zcache_workmem, cpu)); + per_cpu(zcache_workmem, cpu) = NULL; + kp = &per_cpu(zcache_preloads, cpu); + while (kp->nr) { + kmem_cache_free(zcache_objnode_cache, + kp->objnodes[kp->nr - 1]); + kp->objnodes[kp->nr - 1] = NULL; + kp->nr--; + } + if (kp->obj) { + kmem_cache_free(zcache_obj_cache, kp->obj); + kp->obj = NULL; + } + if (kp->page) { + free_page((unsigned long)kp->page); + kp->page = NULL; + } + break; + default: + break; + } + return NOTIFY_OK; +} + +static struct notifier_block zcache_cpu_notifier_block = { + .notifier_call = zcache_cpu_notifier +}; + +#ifdef CONFIG_SYSFS +#define ZCACHE_SYSFS_RO(_name) \ + static ssize_t zcache_##_name##_show(struct kobject *kobj, \ + struct kobj_attribute *attr, char *buf) \ + { \ + return sprintf(buf, "%lu\n", zcache_##_name); \ + } \ + static struct kobj_attribute zcache_##_name##_attr = { \ + .attr = { .name = __stringify(_name), .mode = 0444 }, \ + .show = zcache_##_name##_show, \ + } + +#define ZCACHE_SYSFS_RO_ATOMIC(_name) \ + static ssize_t zcache_##_name##_show(struct kobject *kobj, \ + struct kobj_attribute *attr, char *buf) \ + { \ + return sprintf(buf, "%d\n", atomic_read(&zcache_##_name)); \ + } \ + static struct kobj_attribute zcache_##_name##_attr = { \ + .attr = { .name = __stringify(_name), .mode = 0444 }, \ + .show = zcache_##_name##_show, \ + } + +#define ZCACHE_SYSFS_RO_CUSTOM(_name, _func) \ + static ssize_t zcache_##_name##_show(struct kobject *kobj, \ + struct kobj_attribute *attr, char *buf) \ + { \ + return _func(buf); \ + } \ + static struct kobj_attribute zcache_##_name##_attr = { \ + .attr = { .name = __stringify(_name), .mode = 0444 }, \ + .show = zcache_##_name##_show, \ + } + +ZCACHE_SYSFS_RO(curr_obj_count_max); +ZCACHE_SYSFS_RO(curr_objnode_count_max); +ZCACHE_SYSFS_RO(flush_total); +ZCACHE_SYSFS_RO(flush_found); +ZCACHE_SYSFS_RO(flobj_total); +ZCACHE_SYSFS_RO(flobj_found); +ZCACHE_SYSFS_RO(failed_eph_puts); +ZCACHE_SYSFS_RO(failed_pers_puts); +ZCACHE_SYSFS_RO(zbud_curr_zbytes); +ZCACHE_SYSFS_RO(zbud_cumul_zpages); +ZCACHE_SYSFS_RO(zbud_cumul_zbytes); +ZCACHE_SYSFS_RO(zbud_buddied_count); +ZCACHE_SYSFS_RO(zbpg_unused_list_count); +ZCACHE_SYSFS_RO(evicted_raw_pages); +ZCACHE_SYSFS_RO(evicted_unbuddied_pages); +ZCACHE_SYSFS_RO(evicted_buddied_pages); +ZCACHE_SYSFS_RO(failed_get_free_pages); +ZCACHE_SYSFS_RO(failed_alloc); +ZCACHE_SYSFS_RO(put_to_flush); +ZCACHE_SYSFS_RO(compress_poor); +ZCACHE_SYSFS_RO(mean_compress_poor); +ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_raw_pages); +ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_zpages); +ZCACHE_SYSFS_RO_ATOMIC(curr_obj_count); +ZCACHE_SYSFS_RO_ATOMIC(curr_objnode_count); +ZCACHE_SYSFS_RO_CUSTOM(zbud_unbuddied_list_counts, + zbud_show_unbuddied_list_counts); +ZCACHE_SYSFS_RO_CUSTOM(zbud_cumul_chunk_counts, + zbud_show_cumul_chunk_counts); +ZCACHE_SYSFS_RO_CUSTOM(zv_curr_dist_counts, + zv_curr_dist_counts_show); +ZCACHE_SYSFS_RO_CUSTOM(zv_cumul_dist_counts, + zv_cumul_dist_counts_show); + +static struct attribute *zcache_attrs[] = { + &zcache_curr_obj_count_attr.attr, + &zcache_curr_obj_count_max_attr.attr, + &zcache_curr_objnode_count_attr.attr, + &zcache_curr_objnode_count_max_attr.attr, + &zcache_flush_total_attr.attr, + &zcache_flobj_total_attr.attr, + &zcache_flush_found_attr.attr, + &zcache_flobj_found_attr.attr, + &zcache_failed_eph_puts_attr.attr, + &zcache_failed_pers_puts_attr.attr, + &zcache_compress_poor_attr.attr, + &zcache_mean_compress_poor_attr.attr, + &zcache_zbud_curr_raw_pages_attr.attr, + &zcache_zbud_curr_zpages_attr.attr, + &zcache_zbud_curr_zbytes_attr.attr, + &zcache_zbud_cumul_zpages_attr.attr, + &zcache_zbud_cumul_zbytes_attr.attr, + &zcache_zbud_buddied_count_attr.attr, + &zcache_zbpg_unused_list_count_attr.attr, + &zcache_evicted_raw_pages_attr.attr, + &zcache_evicted_unbuddied_pages_attr.attr, + &zcache_evicted_buddied_pages_attr.attr, + &zcache_failed_get_free_pages_attr.attr, + &zcache_failed_alloc_attr.attr, + &zcache_put_to_flush_attr.attr, + &zcache_zbud_unbuddied_list_counts_attr.attr, + &zcache_zbud_cumul_chunk_counts_attr.attr, + &zcache_zv_curr_dist_counts_attr.attr, + &zcache_zv_cumul_dist_counts_attr.attr, + &zcache_zv_max_zsize_attr.attr, + &zcache_zv_max_mean_zsize_attr.attr, + &zcache_zv_page_count_policy_percent_attr.attr, + NULL, +}; + +static struct attribute_group zcache_attr_group = { + .attrs = zcache_attrs, + .name = "zcache", +}; + +#endif /* CONFIG_SYSFS */ +/* + * When zcache is disabled ("frozen"), pools can be created and destroyed, + * but all puts (and thus all other operations that require memory allocation) + * must fail. If zcache is unfrozen, accepts puts, then frozen again, + * data consistency requires all puts while frozen to be converted into + * flushes. + */ +static bool zcache_freeze; + +/* + * zcache shrinker interface (only useful for ephemeral pages, so zbud only) + */ +static int shrink_zcache_memory(struct shrinker *shrink, + struct shrink_control *sc) +{ + int ret = -1; + int nr = sc->nr_to_scan; + gfp_t gfp_mask = sc->gfp_mask; + + if (nr >= 0) { + if (!(gfp_mask & __GFP_FS)) + /* does this case really need to be skipped? */ + goto out; + zbud_evict_pages(nr); + } + ret = (int)atomic_read(&zcache_zbud_curr_raw_pages); +out: + return ret; +} + +static struct shrinker zcache_shrinker = { + .shrink = shrink_zcache_memory, + .seeks = DEFAULT_SEEKS, +}; + +/* + * zcache shims between cleancache/frontswap ops and tmem + */ + +static int zcache_put_page(int cli_id, int pool_id, struct tmem_oid *oidp, + uint32_t index, struct page *page) +{ + struct tmem_pool *pool; + int ret = -1; + + BUG_ON(!irqs_disabled()); + pool = zcache_get_pool_by_id(cli_id, pool_id); + if (unlikely(pool == NULL)) + goto out; + if (!zcache_freeze && zcache_do_preload(pool) == 0) { + /* preload does preempt_disable on success */ + ret = tmem_put(pool, oidp, index, (char *)(page), + PAGE_SIZE, 0, is_ephemeral(pool)); + if (ret < 0) { + if (is_ephemeral(pool)) + zcache_failed_eph_puts++; + else + zcache_failed_pers_puts++; + } + zcache_put_pool(pool); + preempt_enable_no_resched(); + } else { + zcache_put_to_flush++; + if (atomic_read(&pool->obj_count) > 0) + /* the put fails whether the flush succeeds or not */ + (void)tmem_flush_page(pool, oidp, index); + zcache_put_pool(pool); + } +out: + return ret; +} + +static int zcache_get_page(int cli_id, int pool_id, struct tmem_oid *oidp, + uint32_t index, struct page *page) +{ + struct tmem_pool *pool; + int ret = -1; + unsigned long flags; + size_t size = PAGE_SIZE; + + local_irq_save(flags); + pool = zcache_get_pool_by_id(cli_id, pool_id); + if (likely(pool != NULL)) { + if (atomic_read(&pool->obj_count) > 0) + ret = tmem_get(pool, oidp, index, (char *)(page), + &size, 0, is_ephemeral(pool)); + zcache_put_pool(pool); + } + local_irq_restore(flags); + return ret; +} + +static int zcache_flush_page(int cli_id, int pool_id, + struct tmem_oid *oidp, uint32_t index) +{ + struct tmem_pool *pool; + int ret = -1; + unsigned long flags; + + local_irq_save(flags); + zcache_flush_total++; + pool = zcache_get_pool_by_id(cli_id, pool_id); + if (likely(pool != NULL)) { + if (atomic_read(&pool->obj_count) > 0) + ret = tmem_flush_page(pool, oidp, index); + zcache_put_pool(pool); + } + if (ret >= 0) + zcache_flush_found++; + local_irq_restore(flags); + return ret; +} + +static int zcache_flush_object(int cli_id, int pool_id, + struct tmem_oid *oidp) +{ + struct tmem_pool *pool; + int ret = -1; + unsigned long flags; + + local_irq_save(flags); + zcache_flobj_total++; + pool = zcache_get_pool_by_id(cli_id, pool_id); + if (likely(pool != NULL)) { + if (atomic_read(&pool->obj_count) > 0) + ret = tmem_flush_object(pool, oidp); + zcache_put_pool(pool); + } + if (ret >= 0) + zcache_flobj_found++; + local_irq_restore(flags); + return ret; +} + +static int zcache_destroy_pool(int cli_id, int pool_id) +{ + struct tmem_pool *pool = NULL; + struct zcache_client *cli = NULL; + int ret = -1; + + if (pool_id < 0) + goto out; + if (cli_id == LOCAL_CLIENT) + cli = &zcache_host; + else if ((unsigned int)cli_id < MAX_CLIENTS) + cli = &zcache_clients[cli_id]; + if (cli == NULL) + goto out; + atomic_inc(&cli->refcount); + pool = cli->tmem_pools[pool_id]; + if (pool == NULL) + goto out; + cli->tmem_pools[pool_id] = NULL; + /* wait for pool activity on other cpus to quiesce */ + while (atomic_read(&pool->refcount) != 0) + ; + atomic_dec(&cli->refcount); + local_bh_disable(); + ret = tmem_destroy_pool(pool); + local_bh_enable(); + kfree(pool); + pr_info("zcache: destroyed pool id=%d, cli_id=%d\n", + pool_id, cli_id); +out: + return ret; +} + +static int zcache_new_pool(uint16_t cli_id, uint32_t flags) +{ + int poolid = -1; + struct tmem_pool *pool; + struct zcache_client *cli = NULL; + + if (cli_id == LOCAL_CLIENT) + cli = &zcache_host; + else if ((unsigned int)cli_id < MAX_CLIENTS) + cli = &zcache_clients[cli_id]; + if (cli == NULL) + goto out; + atomic_inc(&cli->refcount); + pool = kmalloc(sizeof(struct tmem_pool), GFP_ATOMIC); + if (pool == NULL) { + pr_info("zcache: pool creation failed: out of memory\n"); + goto out; + } + + for (poolid = 0; poolid < MAX_POOLS_PER_CLIENT; poolid++) + if (cli->tmem_pools[poolid] == NULL) + break; + if (poolid >= MAX_POOLS_PER_CLIENT) { + pr_info("zcache: pool creation failed: max exceeded\n"); + kfree(pool); + poolid = -1; + goto out; + } + atomic_set(&pool->refcount, 0); + pool->client = cli; + pool->pool_id = poolid; + tmem_new_pool(pool, flags); + cli->tmem_pools[poolid] = pool; + pr_info("zcache: created %s tmem pool, id=%d, client=%d\n", + flags & TMEM_POOL_PERSIST ? "persistent" : "ephemeral", + poolid, cli_id); +out: + if (cli != NULL) + atomic_dec(&cli->refcount); + return poolid; +} + +/********** + * Two kernel functionalities currently can be layered on top of tmem. + * These are "cleancache" which is used as a second-chance cache for clean + * page cache pages; and "frontswap" which is used for swap pages + * to avoid writes to disk. A generic "shim" is provided here for each + * to translate in-kernel semantics to zcache semantics. + */ + +#ifdef CONFIG_CLEANCACHE +static void zcache_cleancache_put_page(int pool_id, + struct cleancache_filekey key, + pgoff_t index, struct page *page) +{ + u32 ind = (u32) index; + struct tmem_oid oid = *(struct tmem_oid *)&key; + + if (likely(ind == index)) + (void)zcache_put_page(LOCAL_CLIENT, pool_id, &oid, index, page); +} + +static int zcache_cleancache_get_page(int pool_id, + struct cleancache_filekey key, + pgoff_t index, struct page *page) +{ + u32 ind = (u32) index; + struct tmem_oid oid = *(struct tmem_oid *)&key; + int ret = -1; + + if (likely(ind == index)) + ret = zcache_get_page(LOCAL_CLIENT, pool_id, &oid, index, page); + return ret; +} + +static void zcache_cleancache_flush_page(int pool_id, + struct cleancache_filekey key, + pgoff_t index) +{ + u32 ind = (u32) index; + struct tmem_oid oid = *(struct tmem_oid *)&key; + + if (likely(ind == index)) + (void)zcache_flush_page(LOCAL_CLIENT, pool_id, &oid, ind); +} + +static void zcache_cleancache_flush_inode(int pool_id, + struct cleancache_filekey key) +{ + struct tmem_oid oid = *(struct tmem_oid *)&key; + + (void)zcache_flush_object(LOCAL_CLIENT, pool_id, &oid); +} + +static void zcache_cleancache_flush_fs(int pool_id) +{ + if (pool_id >= 0) + (void)zcache_destroy_pool(LOCAL_CLIENT, pool_id); +} + +static int zcache_cleancache_init_fs(size_t pagesize) +{ + BUG_ON(sizeof(struct cleancache_filekey) != + sizeof(struct tmem_oid)); + BUG_ON(pagesize != PAGE_SIZE); + return zcache_new_pool(LOCAL_CLIENT, 0); +} + +static int zcache_cleancache_init_shared_fs(char *uuid, size_t pagesize) +{ + /* shared pools are unsupported and map to private */ + BUG_ON(sizeof(struct cleancache_filekey) != + sizeof(struct tmem_oid)); + BUG_ON(pagesize != PAGE_SIZE); + return zcache_new_pool(LOCAL_CLIENT, 0); +} + +static struct cleancache_ops zcache_cleancache_ops = { + .put_page = zcache_cleancache_put_page, + .get_page = zcache_cleancache_get_page, + .invalidate_page = zcache_cleancache_flush_page, + .invalidate_inode = zcache_cleancache_flush_inode, + .invalidate_fs = zcache_cleancache_flush_fs, + .init_shared_fs = zcache_cleancache_init_shared_fs, + .init_fs = zcache_cleancache_init_fs +}; + +struct cleancache_ops zcache_cleancache_register_ops(void) +{ + struct cleancache_ops old_ops = + cleancache_register_ops(&zcache_cleancache_ops); + + return old_ops; +} +#endif + +#ifdef CONFIG_FRONTSWAP +/* a single tmem poolid is used for all frontswap "types" (swapfiles) */ +static int zcache_frontswap_poolid = -1; + +/* + * Swizzling increases objects per swaptype, increasing tmem concurrency + * for heavy swaploads. Later, larger nr_cpus -> larger SWIZ_BITS + * Setting SWIZ_BITS to 27 basically reconstructs the swap entry from + * frontswap_get_page() + */ +#define SWIZ_BITS 27 +#define SWIZ_MASK ((1 << SWIZ_BITS) - 1) +#define _oswiz(_type, _ind) ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK)) +#define iswiz(_ind) (_ind >> SWIZ_BITS) + +static inline struct tmem_oid oswiz(unsigned type, u32 ind) +{ + struct tmem_oid oid = { .oid = { 0 } }; + oid.oid[0] = _oswiz(type, ind); + return oid; +} + +static int zcache_frontswap_put_page(unsigned type, pgoff_t offset, + struct page *page) +{ + u64 ind64 = (u64)offset; + u32 ind = (u32)offset; + struct tmem_oid oid = oswiz(type, ind); + int ret = -1; + unsigned long flags; + + BUG_ON(!PageLocked(page)); + if (likely(ind64 == ind)) { + local_irq_save(flags); + ret = zcache_put_page(LOCAL_CLIENT, zcache_frontswap_poolid, + &oid, iswiz(ind), page); + local_irq_restore(flags); + } + return ret; +} + +/* returns 0 if the page was successfully gotten from frontswap, -1 if + * was not present (should never happen!) */ +static int zcache_frontswap_get_page(unsigned type, pgoff_t offset, + struct page *page) +{ + u64 ind64 = (u64)offset; + u32 ind = (u32)offset; + struct tmem_oid oid = oswiz(type, ind); + int ret = -1; + + BUG_ON(!PageLocked(page)); + if (likely(ind64 == ind)) + ret = zcache_get_page(LOCAL_CLIENT, zcache_frontswap_poolid, + &oid, iswiz(ind), page); + return ret; +} + +/* flush a single page from frontswap */ +static void zcache_frontswap_flush_page(unsigned type, pgoff_t offset) +{ + u64 ind64 = (u64)offset; + u32 ind = (u32)offset; + struct tmem_oid oid = oswiz(type, ind); + + if (likely(ind64 == ind)) + (void)zcache_flush_page(LOCAL_CLIENT, zcache_frontswap_poolid, + &oid, iswiz(ind)); +} + +/* flush all pages from the passed swaptype */ +static void zcache_frontswap_flush_area(unsigned type) +{ + struct tmem_oid oid; + int ind; + + for (ind = SWIZ_MASK; ind >= 0; ind--) { + oid = oswiz(type, ind); + (void)zcache_flush_object(LOCAL_CLIENT, + zcache_frontswap_poolid, &oid); + } +} + +static void zcache_frontswap_init(unsigned ignored) +{ + /* a single tmem poolid is used for all frontswap "types" (swapfiles) */ + if (zcache_frontswap_poolid < 0) + zcache_frontswap_poolid = + zcache_new_pool(LOCAL_CLIENT, TMEM_POOL_PERSIST); +} + +static struct frontswap_ops zcache_frontswap_ops = { + .put_page = zcache_frontswap_put_page, + .get_page = zcache_frontswap_get_page, + .invalidate_page = zcache_frontswap_flush_page, + .invalidate_area = zcache_frontswap_flush_area, + .init = zcache_frontswap_init +}; + +struct frontswap_ops zcache_frontswap_register_ops(void) +{ + struct frontswap_ops old_ops = + frontswap_register_ops(&zcache_frontswap_ops); + + return old_ops; +} +#endif + +/* + * zcache initialization + * NOTE FOR NOW zcache MUST BE PROVIDED AS A KERNEL BOOT PARAMETER OR + * NOTHING HAPPENS! + */ + +static int zcache_enabled; + +static int __init enable_zcache(char *s) +{ + zcache_enabled = 1; + return 1; +} +__setup("zcache", enable_zcache); + +/* allow independent dynamic disabling of cleancache and frontswap */ + +static int use_cleancache = 1; + +static int __init no_cleancache(char *s) +{ + use_cleancache = 0; + return 1; +} + +__setup("nocleancache", no_cleancache); + +static int use_frontswap = 1; + +static int __init no_frontswap(char *s) +{ + use_frontswap = 0; + return 1; +} + +__setup("nofrontswap", no_frontswap); + +static int __init zcache_init(void) +{ + int ret = 0; + +#ifdef CONFIG_SYSFS + ret = sysfs_create_group(mm_kobj, &zcache_attr_group); + if (ret) { + pr_err("zcache: can't create sysfs\n"); + goto out; + } +#endif /* CONFIG_SYSFS */ +#if defined(CONFIG_CLEANCACHE) || defined(CONFIG_FRONTSWAP) + if (zcache_enabled) { + unsigned int cpu; + + tmem_register_hostops(&zcache_hostops); + tmem_register_pamops(&zcache_pamops); + ret = register_cpu_notifier(&zcache_cpu_notifier_block); + if (ret) { + pr_err("zcache: can't register cpu notifier\n"); + goto out; + } + for_each_online_cpu(cpu) { + void *pcpu = (void *)(long)cpu; + zcache_cpu_notifier(&zcache_cpu_notifier_block, + CPU_UP_PREPARE, pcpu); + } + } + zcache_objnode_cache = kmem_cache_create("zcache_objnode", + sizeof(struct tmem_objnode), 0, 0, NULL); + zcache_obj_cache = kmem_cache_create("zcache_obj", + sizeof(struct tmem_obj), 0, 0, NULL); + ret = zcache_new_client(LOCAL_CLIENT); + if (ret) { + pr_err("zcache: can't create client\n"); + goto out; + } +#endif +#ifdef CONFIG_CLEANCACHE + if (zcache_enabled && use_cleancache) { + struct cleancache_ops old_ops; + + zbud_init(); + register_shrinker(&zcache_shrinker); + old_ops = zcache_cleancache_register_ops(); + pr_info("zcache: cleancache enabled using kernel " + "transcendent memory and compression buddies\n"); + if (old_ops.init_fs != NULL) + pr_warning("zcache: cleancache_ops overridden"); + } +#endif +#ifdef CONFIG_FRONTSWAP + if (zcache_enabled && use_frontswap) { + struct frontswap_ops old_ops; + + old_ops = zcache_frontswap_register_ops(); + pr_info("zcache: frontswap enabled using kernel " + "transcendent memory and xvmalloc\n"); + if (old_ops.init != NULL) + pr_warning("zcache: frontswap_ops overridden"); + } +#endif +out: + return ret; +} + +module_init(zcache_init) -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/