Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751379AbVK2PWZ (ORCPT ); Tue, 29 Nov 2005 10:22:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751381AbVK2PWZ (ORCPT ); Tue, 29 Nov 2005 10:22:25 -0500 Received: from gw1.cosmosbay.com ([62.23.185.226]:26597 "EHLO gw1.cosmosbay.com") by vger.kernel.org with ESMTP id S1751378AbVK2PWY (ORCPT ); Tue, 29 Nov 2005 10:22:24 -0500 Message-ID: <438C7218.8030109@cosmosbay.com> Date: Tue, 29 Nov 2005 16:22:00 +0100 From: Eric Dumazet User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: fr, en MIME-Version: 1.0 To: Andrew Morton CC: linux-kernel@vger.kernel.org Subject: [PATCH] shrinks dentry struct References: <121a28810511282317j47a90f6t@mail.gmail.com> <20051129000916.6306da8b.akpm@osdl.org> In-Reply-To: <20051129000916.6306da8b.akpm@osdl.org> Content-Type: multipart/mixed; boundary="------------040309060707080901060909" X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-1.6 (gw1.cosmosbay.com [172.16.8.80]); Tue, 29 Nov 2005 16:21:57 +0100 (CET) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 16544 Lines: 482 This is a multi-part message in MIME format. --------------040309060707080901060909 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi Andrew Could you add this patch to mm ? Thank you [PATCH] shrinks dentry struct Some long time ago, dentry struct was carefully tuned so that on 32 bits UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple of memory cache lines. Then RCU was added and dentry struct enlarged by two pointers, with nice results for SMP, but not so good on UP, because breaking the above tuning (128 + 8 = 136 bytes) This patch reverts this unwanted side effect, by using an union (d_u), where d_rcu and d_child are placed so that these two fields can share their memory needs. At the time d_free() is called (and d_rcu is really used), d_child is known to be empty and not touched by the dentry freeing. Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so the previous content of d_child is not needed if said dentry was unhashed but still accessed by a CPU because of RCU constraints) As dentry cache easily contains millions of entries, a size reduction is worth the extra complexity of the ugly C union. Signed-off-by: Eric Dumazet --------------040309060707080901060909 Content-Type: text/plain; name="shrink_dentry_struct.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="shrink_dentry_struct.patch" --- linux-2.6.15-rc3/include/linux/dcache.h 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/include/linux/dcache.h 2005-11-29 12:04:54.000000000 +0100 @@ -95,14 +95,19 @@ struct qstr d_name; struct list_head d_lru; /* LRU list */ - struct list_head d_child; /* child of parent list */ + /* + * d_child and d_rcu can share memory + */ + union { + struct list_head d_child; /* child of parent list */ + struct rcu_head d_rcu; + } d_u; struct list_head d_subdirs; /* our children */ struct list_head d_alias; /* inode alias list */ unsigned long d_time; /* used by d_revalidate */ struct dentry_operations *d_op; struct super_block *d_sb; /* The root of the dentry tree */ void *d_fsdata; /* fs-specific data */ - struct rcu_head d_rcu; struct dcookie_struct *d_cookie; /* cookie, if any */ int d_mounted; unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */ --- linux-2.6.15-rc3/fs/dcache.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/fs/dcache.c 2005-11-29 15:07:10.000000000 +0100 @@ -71,7 +71,7 @@ static void d_callback(struct rcu_head *head) { - struct dentry * dentry = container_of(head, struct dentry, d_rcu); + struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu); if (dname_external(dentry)) kfree(dentry->d_name.name); @@ -86,7 +86,7 @@ { if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); - call_rcu(&dentry->d_rcu, d_callback); + call_rcu(&dentry->d_u.d_rcu, d_callback); } /* @@ -193,7 +193,7 @@ list_del(&dentry->d_lru); dentry_stat.nr_unused--; } - list_del(&dentry->d_child); + list_del(&dentry->d_u.d_child); dentry_stat.nr_dentry--; /* For d_free, below */ /*drops the locks, at that point nobody can reach this dentry */ dentry_iput(dentry); @@ -367,7 +367,7 @@ struct dentry * parent; __d_drop(dentry); - list_del(&dentry->d_child); + list_del(&dentry->d_u.d_child); dentry_stat.nr_dentry--; /* For d_free, below */ dentry_iput(dentry); parent = dentry->d_parent; @@ -518,7 +518,7 @@ resume: while (next != &this_parent->d_subdirs) { struct list_head *tmp = next; - struct dentry *dentry = list_entry(tmp, struct dentry, d_child); + struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); next = tmp->next; /* Have we found a mount point ? */ if (d_mountpoint(dentry)) @@ -532,7 +532,7 @@ * All done at this level ... ascend and resume the search. */ if (this_parent != parent) { - next = this_parent->d_child.next; + next = this_parent->d_u.d_child.next; this_parent = this_parent->d_parent; goto resume; } @@ -569,7 +569,7 @@ resume: while (next != &this_parent->d_subdirs) { struct list_head *tmp = next; - struct dentry *dentry = list_entry(tmp, struct dentry, d_child); + struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); next = tmp->next; if (!list_empty(&dentry->d_lru)) { @@ -610,7 +610,7 @@ * All done at this level ... ascend and resume the search. */ if (this_parent != parent) { - next = this_parent->d_child.next; + next = this_parent->d_u.d_child.next; this_parent = this_parent->d_parent; #ifdef DCACHE_DEBUG printk(KERN_DEBUG "select_parent: ascending to %s/%s, found=%d\n", @@ -753,12 +753,12 @@ dentry->d_parent = dget(parent); dentry->d_sb = parent->d_sb; } else { - INIT_LIST_HEAD(&dentry->d_child); + INIT_LIST_HEAD(&dentry->d_u.d_child); } spin_lock(&dcache_lock); if (parent) - list_add(&dentry->d_child, &parent->d_subdirs); + list_add(&dentry->d_u.d_child, &parent->d_subdirs); dentry_stat.nr_dentry++; spin_unlock(&dcache_lock); @@ -1310,8 +1310,8 @@ /* Unhash the target: dput() will then get rid of it */ __d_drop(target); - list_del(&dentry->d_child); - list_del(&target->d_child); + list_del(&dentry->d_u.d_child); + list_del(&target->d_u.d_child); /* Switch the names.. */ switch_names(dentry, target); @@ -1322,15 +1322,15 @@ if (IS_ROOT(dentry)) { dentry->d_parent = target->d_parent; target->d_parent = target; - INIT_LIST_HEAD(&target->d_child); + INIT_LIST_HEAD(&target->d_u.d_child); } else { do_switch(dentry->d_parent, target->d_parent); /* And add them back to the (new) parent lists */ - list_add(&target->d_child, &target->d_parent->d_subdirs); + list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); } - list_add(&dentry->d_child, &dentry->d_parent->d_subdirs); + list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); spin_unlock(&target->d_lock); spin_unlock(&dentry->d_lock); write_sequnlock(&rename_lock); @@ -1568,7 +1568,7 @@ resume: while (next != &this_parent->d_subdirs) { struct list_head *tmp = next; - struct dentry *dentry = list_entry(tmp, struct dentry, d_child); + struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); next = tmp->next; if (d_unhashed(dentry)||!dentry->d_inode) continue; @@ -1579,7 +1579,7 @@ atomic_dec(&dentry->d_count); } if (this_parent != root) { - next = this_parent->d_child.next; + next = this_parent->d_u.d_child.next; atomic_dec(&this_parent->d_count); this_parent = this_parent->d_parent; goto resume; --- linux-2.6.15-rc3/fs/autofs4/autofs_i.h 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/fs/autofs4/autofs_i.h 2005-11-29 12:04:54.000000000 +0100 @@ -209,7 +209,7 @@ struct dentry *child; int ret = 0; - list_for_each_entry(child, &dentry->d_subdirs, d_child) + list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) if (simple_positive(child)) goto out; ret = 1; --- linux-2.6.15-rc3/fs/autofs4/expire.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/fs/autofs4/expire.c 2005-11-29 12:04:54.000000000 +0100 @@ -105,7 +105,7 @@ next = this_parent->d_subdirs.next; resume: while (next != &this_parent->d_subdirs) { - struct dentry *dentry = list_entry(next, struct dentry, d_child); + struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child); /* Negative dentry - give up */ if (!simple_positive(dentry)) { @@ -138,7 +138,7 @@ } if (this_parent != top) { - next = this_parent->d_child.next; + next = this_parent->d_u.d_child.next; this_parent = this_parent->d_parent; goto resume; } @@ -163,7 +163,7 @@ next = this_parent->d_subdirs.next; resume: while (next != &this_parent->d_subdirs) { - struct dentry *dentry = list_entry(next, struct dentry, d_child); + struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child); /* Negative dentry - give up */ if (!simple_positive(dentry)) { @@ -199,7 +199,7 @@ } if (this_parent != parent) { - next = this_parent->d_child.next; + next = this_parent->d_u.d_child.next; this_parent = this_parent->d_parent; goto resume; } @@ -238,7 +238,7 @@ /* On exit from the loop expire is set to a dgot dentry * to expire or it's NULL */ while ( next != &root->d_subdirs ) { - struct dentry *dentry = list_entry(next, struct dentry, d_child); + struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child); /* Negative dentry - give up */ if ( !simple_positive(dentry) ) { @@ -302,7 +302,7 @@ expired, (int)expired->d_name.len, expired->d_name.name); spin_lock(&dcache_lock); list_del(&expired->d_parent->d_subdirs); - list_add(&expired->d_parent->d_subdirs, &expired->d_child); + list_add(&expired->d_parent->d_subdirs, &expired->d_u.d_child); spin_unlock(&dcache_lock); return expired; } --- linux-2.6.15-rc3/fs/autofs4/inode.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/fs/autofs4/inode.c 2005-11-29 12:04:54.000000000 +0100 @@ -91,7 +91,7 @@ next = this_parent->d_subdirs.next; resume: while (next != &this_parent->d_subdirs) { - struct dentry *dentry = list_entry(next, struct dentry, d_child); + struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child); /* Negative dentry - don`t care */ if (!simple_positive(dentry)) { @@ -117,7 +117,7 @@ if (this_parent != sbi->root) { struct dentry *dentry = this_parent; - next = this_parent->d_child.next; + next = this_parent->d_u.d_child.next; this_parent = this_parent->d_parent; spin_unlock(&dcache_lock); DPRINTK("parent dentry %p %.*s", --- linux-2.6.15-rc3/fs/coda/cache.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/fs/coda/cache.c 2005-11-29 12:05:21.000000000 +0100 @@ -93,7 +93,7 @@ spin_lock(&dcache_lock); list_for_each(child, &parent->d_subdirs) { - de = list_entry(child, struct dentry, d_child); + de = list_entry(child, struct dentry, d_u.d_child); /* don't know what to do with negative dentries */ if ( ! de->d_inode ) continue; --- linux-2.6.15-rc3/fs/libfs.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/fs/libfs.c 2005-11-29 14:58:51.000000000 +0100 @@ -93,16 +93,16 @@ loff_t n = file->f_pos - 2; spin_lock(&dcache_lock); - list_del(&cursor->d_child); + list_del(&cursor->d_u.d_child); p = file->f_dentry->d_subdirs.next; while (n && p != &file->f_dentry->d_subdirs) { struct dentry *next; - next = list_entry(p, struct dentry, d_child); + next = list_entry(p, struct dentry, d_u.d_child); if (!d_unhashed(next) && next->d_inode) n--; p = p->next; } - list_add_tail(&cursor->d_child, p); + list_add_tail(&cursor->d_u.d_child, p); spin_unlock(&dcache_lock); } } @@ -126,7 +126,7 @@ { struct dentry *dentry = filp->f_dentry; struct dentry *cursor = filp->private_data; - struct list_head *p, *q = &cursor->d_child; + struct list_head *p, *q = &cursor->d_u.d_child; ino_t ino; int i = filp->f_pos; @@ -153,7 +153,7 @@ } for (p=q->next; p != &dentry->d_subdirs; p=p->next) { struct dentry *next; - next = list_entry(p, struct dentry, d_child); + next = list_entry(p, struct dentry, d_u.d_child); if (d_unhashed(next) || !next->d_inode) continue; @@ -261,7 +261,7 @@ int ret = 0; spin_lock(&dcache_lock); - list_for_each_entry(child, &dentry->d_subdirs, d_child) + list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) if (simple_positive(child)) goto out; ret = 1; --- linux-2.6.15-rc3/fs/ncpfs/dir.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/fs/ncpfs/dir.c 2005-11-29 14:59:31.000000000 +0100 @@ -365,7 +365,7 @@ spin_lock(&dcache_lock); next = parent->d_subdirs.next; while (next != &parent->d_subdirs) { - dent = list_entry(next, struct dentry, d_child); + dent = list_entry(next, struct dentry, d_u.d_child); if ((unsigned long)dent->d_fsdata == fpos) { if (dent->d_inode) dget_locked(dent); --- linux-2.6.15-rc3/fs/ncpfs/ncplib_kernel.h 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/fs/ncpfs/ncplib_kernel.h 2005-11-29 14:59:31.000000000 +0100 @@ -196,7 +196,7 @@ spin_lock(&dcache_lock); next = parent->d_subdirs.next; while (next != &parent->d_subdirs) { - dentry = list_entry(next, struct dentry, d_child); + dentry = list_entry(next, struct dentry, d_u.d_child); if (dentry->d_fsdata == NULL) ncp_age_dentry(server, dentry); @@ -218,7 +218,7 @@ spin_lock(&dcache_lock); next = parent->d_subdirs.next; while (next != &parent->d_subdirs) { - dentry = list_entry(next, struct dentry, d_child); + dentry = list_entry(next, struct dentry, d_u.d_child); dentry->d_fsdata = NULL; ncp_age_dentry(server, dentry); next = next->next; --- linux-2.6.15-rc3/fs/smbfs/cache.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/fs/smbfs/cache.c 2005-11-29 14:59:47.000000000 +0100 @@ -66,7 +66,7 @@ spin_lock(&dcache_lock); next = parent->d_subdirs.next; while (next != &parent->d_subdirs) { - dentry = list_entry(next, struct dentry, d_child); + dentry = list_entry(next, struct dentry, d_u.d_child); dentry->d_fsdata = NULL; smb_age_dentry(server, dentry); next = next->next; @@ -100,7 +100,7 @@ spin_lock(&dcache_lock); next = parent->d_subdirs.next; while (next != &parent->d_subdirs) { - dent = list_entry(next, struct dentry, d_child); + dent = list_entry(next, struct dentry, d_u.d_child); if ((unsigned long)dent->d_fsdata == fpos) { if (dent->d_inode) dget_locked(dent); --- linux-2.6.15-rc3/kernel/cpuset.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/kernel/cpuset.c 2005-11-29 15:01:01.000000000 +0100 @@ -304,7 +304,7 @@ spin_lock(&dcache_lock); node = dentry->d_subdirs.next; while (node != &dentry->d_subdirs) { - struct dentry *d = list_entry(node, struct dentry, d_child); + struct dentry *d = list_entry(node, struct dentry, d_u.d_child); list_del_init(node); if (d->d_inode) { d = dget_locked(d); @@ -316,7 +316,7 @@ } node = dentry->d_subdirs.next; } - list_del_init(&dentry->d_child); + list_del_init(&dentry->d_u.d_child); spin_unlock(&dcache_lock); remove_dir(dentry); } --- linux-2.6.15-rc3/drivers/usb/core/inode.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/drivers/usb/core/inode.c 2005-11-29 12:04:54.000000000 +0100 @@ -186,7 +186,7 @@ down(&bus->d_inode->i_sem); - list_for_each_entry(dev, &bus->d_subdirs, d_child) + list_for_each_entry(dev, &bus->d_subdirs, d_u.d_child) if (dev->d_inode) update_dev(dev); @@ -203,7 +203,7 @@ down(&root->d_inode->i_sem); - list_for_each_entry(bus, &root->d_subdirs, d_child) { + list_for_each_entry(bus, &root->d_subdirs, d_u.d_child) { if (bus->d_inode) { switch (S_IFMT & bus->d_inode->i_mode) { case S_IFDIR: @@ -319,7 +319,7 @@ spin_lock(&dcache_lock); list_for_each(list, &dentry->d_subdirs) { - struct dentry *de = list_entry(list, struct dentry, d_child); + struct dentry *de = list_entry(list, struct dentry, d_u.d_child); if (usbfs_positive(de)) { spin_unlock(&dcache_lock); return 0; --- linux-2.6.15-rc3/net/sunrpc/rpc_pipe.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/net/sunrpc/rpc_pipe.c 2005-11-29 15:01:01.000000000 +0100 @@ -492,7 +492,7 @@ repeat: spin_lock(&dcache_lock); list_for_each_safe(pos, next, &parent->d_subdirs) { - dentry = list_entry(pos, struct dentry, d_child); + dentry = list_entry(pos, struct dentry, d_u.d_child); spin_lock(&dentry->d_lock); if (!d_unhashed(dentry)) { dget_locked(dentry); --- linux-2.6.15-rc3/security/selinux/selinuxfs.c 2005-11-29 04:51:27.000000000 +0100 +++ linux-2.6.15-rc3-ed/security/selinux/selinuxfs.c 2005-11-29 15:01:09.000000000 +0100 @@ -889,7 +889,7 @@ spin_lock(&dcache_lock); node = de->d_subdirs.next; while (node != &de->d_subdirs) { - struct dentry *d = list_entry(node, struct dentry, d_child); + struct dentry *d = list_entry(node, struct dentry, d_u.d_child); list_del_init(node); if (d->d_inode) { --------------040309060707080901060909-- - 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/