Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754917Ab3FKLLt (ORCPT ); Tue, 11 Jun 2013 07:11:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:21525 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754741Ab3FKLJx (ORCPT ); Tue, 11 Jun 2013 07:09:53 -0400 From: Jeff Layton To: viro@zeniv.linux.org.uk, matthew@wil.cx, bfields@fieldses.org Cc: dhowells@redhat.com, sage@inktank.com, smfrench@gmail.com, swhiteho@redhat.com, Trond.Myklebust@netapp.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-afs@lists.infradead.org, ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, piastryyy@gmail.com Subject: [PATCH v2 14/14] locks: move file_lock_list to a set of percpu hlist_heads and convert file_lock_lock to an lglock Date: Tue, 11 Jun 2013 07:09:08 -0400 Message-Id: <1370948948-31784-15-git-send-email-jlayton@redhat.com> In-Reply-To: <1370948948-31784-1-git-send-email-jlayton@redhat.com> References: <1370948948-31784-1-git-send-email-jlayton@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5704 Lines: 182 The file_lock_list is only used for /proc/locks. The vastly common case is for locks to be put onto the list and come off again, without ever being traversed. Help optimize for this use-case by moving to percpu hlist_head-s. At the same time, we can make the locking less contentious by moving to an lglock. When iterating over the lists for /proc/locks, we must take the global lock and then iterate over each CPU's list in turn. This change necessitates a new fl_link_cpu field to keep track of which CPU the entry is on. On x86_64 at least, this field is placed within an existing hole in the struct to avoid growing its real size. Signed-off-by: Jeff Layton --- fs/locks.c | 57 +++++++++++++++++++++++++++++++++++---------------- include/linux/fs.h | 1 + 2 files changed, 40 insertions(+), 18 deletions(-) diff --git a/fs/locks.c b/fs/locks.c index 8124fc1..094eb4d 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -127,6 +127,8 @@ #include #include #include +#include +#include #include @@ -165,8 +167,8 @@ int lease_break_time = 45; static DEFINE_SPINLOCK(blocked_hash_lock); static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); -static DEFINE_SPINLOCK(file_lock_lock); -static HLIST_HEAD(file_lock_list); +DEFINE_STATIC_LGLOCK(file_lock_lglock); +static DEFINE_PER_CPU(struct hlist_head, file_lock_list); static struct kmem_cache *filelock_cache __read_mostly; @@ -512,17 +514,21 @@ locks_delete_global_blocked(struct file_lock *waiter) static inline void locks_insert_global_locks(struct file_lock *waiter) { - spin_lock(&file_lock_lock); - hlist_add_head(&waiter->fl_link, &file_lock_list); - spin_unlock(&file_lock_lock); + lg_local_lock(&file_lock_lglock); + waiter->fl_link_cpu = smp_processor_id(); + hlist_add_head(&waiter->fl_link, this_cpu_ptr(&file_lock_list)); + lg_local_unlock(&file_lock_lglock); } static inline void locks_delete_global_locks(struct file_lock *waiter) { - spin_lock(&file_lock_lock); + /* avoid taking lock if already unhashed */ + if (hlist_unhashed(&waiter->fl_link)) + return; + lg_local_lock_cpu(&file_lock_lglock, waiter->fl_link_cpu); hlist_del_init(&waiter->fl_link); - spin_unlock(&file_lock_lock); + lg_local_unlock_cpu(&file_lock_lglock, waiter->fl_link_cpu); } /* Remove waiter from blocker's block list. @@ -2228,6 +2234,11 @@ EXPORT_SYMBOL_GPL(vfs_cancel_lock); #include #include +struct locks_iterator { + int li_cpu; + loff_t li_pos; +}; + static void lock_get_status(struct seq_file *f, struct file_lock *fl, loff_t id, char *pfx) { @@ -2302,16 +2313,17 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, static int locks_show(struct seq_file *f, void *v) { int bkt; + struct locks_iterator *iter = f->private; struct file_lock *fl, *bfl; fl = hlist_entry(v, struct file_lock, fl_link); - lock_get_status(f, fl, *((loff_t *)f->private), ""); + lock_get_status(f, fl, iter->li_pos, ""); spin_lock(&blocked_hash_lock); hash_for_each(blocked_hash, bkt, bfl, fl_link) { if (bfl->fl_next == fl) - lock_get_status(f, bfl, *((loff_t *)f->private), " ->"); + lock_get_status(f, bfl, iter->li_pos, " ->"); } spin_unlock(&blocked_hash_lock); @@ -2320,23 +2332,24 @@ static int locks_show(struct seq_file *f, void *v) static void *locks_start(struct seq_file *f, loff_t *pos) { - loff_t *p = f->private; + struct locks_iterator *iter = f->private; - spin_lock(&file_lock_lock); - *p = (*pos + 1); - return seq_hlist_start(&file_lock_list, *pos); + iter->li_pos = *pos + 1; + lg_global_lock(&file_lock_lglock); + return seq_hlist_start_percpu(&file_lock_list, &iter->li_cpu, *pos); } static void *locks_next(struct seq_file *f, void *v, loff_t *pos) { - loff_t *p = f->private; - ++*p; - return seq_hlist_next(v, &file_lock_list, pos); + struct locks_iterator *iter = f->private; + + ++iter->li_pos; + return seq_hlist_next_percpu(v, &file_lock_list, &iter->li_cpu, pos); } static void locks_stop(struct seq_file *f, void *v) { - spin_unlock(&file_lock_lock); + lg_global_unlock(&file_lock_lglock); } static const struct seq_operations locks_seq_operations = { @@ -2348,7 +2361,8 @@ static const struct seq_operations locks_seq_operations = { static int locks_open(struct inode *inode, struct file *filp) { - return seq_open_private(filp, &locks_seq_operations, sizeof(loff_t)); + return seq_open_private(filp, &locks_seq_operations, + sizeof(struct locks_iterator)); } static const struct file_operations proc_locks_operations = { @@ -2448,9 +2462,16 @@ EXPORT_SYMBOL(lock_may_write); static int __init filelock_init(void) { + int i; + filelock_cache = kmem_cache_create("file_lock_cache", sizeof(struct file_lock), 0, SLAB_PANIC, NULL); + lg_lock_init(&file_lock_lglock, "file_lock_lglock"); + + for_each_possible_cpu(i) + INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list, i)); + return 0; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 232a345..18e59b8 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -953,6 +953,7 @@ struct file_lock { unsigned int fl_flags; unsigned char fl_type; unsigned int fl_pid; + int fl_link_cpu; /* what cpu's list is this on? */ struct pid *fl_nspid; wait_queue_head_t fl_wait; struct file *fl_file; -- 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/