From dfe512fde2b2218d40ff801384e6835322de19dc Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Fri, 7 Jun 2013 10:08:24 +1000 Subject: [PATCH] dcache: convert dentry_stat.nr_unused to per-cpu counters MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Before we split up the dcache_lru_lock, the unused dentry counter needs to be made independent of the global dcache_lru_lock. Convert it to per-cpu counters to do this. Signed-off-by: Dave Chinner Signed-off-by: Glauber Costa Reviewed-by: Christoph Hellwig Acked-by: Mel Gorman Cc: "Theodore Ts'o" Cc: Adrian Hunter Cc: Al Viro Cc: Artem Bityutskiy Cc: Arve Hjønnevåg Cc: Carlos Maiolino Cc: Christoph Hellwig Cc: Chuck Lever Cc: Daniel Vetter Cc: David Rientjes Cc: Gleb Natapov Cc: Greg Thelen Cc: J. Bruce Fields Cc: Jan Kara Cc: Jerome Glisse Cc: John Stultz Cc: KAMEZAWA Hiroyuki Cc: Kent Overstreet Cc: Kirill A. Shutemov Cc: Marcelo Tosatti Cc: Mel Gorman Cc: Steven Whitehouse Cc: Thomas Hellstrom Cc: Trond Myklebust Signed-off-by: Andrew Morton --- fs/dcache.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index aca4e4b12175..0466dbd6bd20 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -118,8 +118,22 @@ struct dentry_stat_t dentry_stat = { }; static DEFINE_PER_CPU(long, nr_dentry); +static DEFINE_PER_CPU(long, nr_dentry_unused); #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) + +/* + * Here we resort to our own counters instead of using generic per-cpu counters + * for consistency with what the vfs inode code does. We are expected to harvest + * better code and performance by having our own specialized counters. + * + * Please note that the loop is done over all possible CPUs, not over all online + * CPUs. The reason for this is that we don't want to play games with CPUs going + * on and off. If one of them goes off, we will just keep their counters. + * + * glommer: See cffbc8a for details, and if you ever intend to change this, + * please update all vfs counters to match. + */ static long get_nr_dentry(void) { int i; @@ -129,10 +143,20 @@ static long get_nr_dentry(void) return sum < 0 ? 0 : sum; } +static long get_nr_dentry_unused(void) +{ + int i; + long sum = 0; + for_each_possible_cpu(i) + sum += per_cpu(nr_dentry_unused, i); + return sum < 0 ? 0 : sum; +} + int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { dentry_stat.nr_dentry = get_nr_dentry(); + dentry_stat.nr_unused = get_nr_dentry_unused(); return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); } #endif @@ -312,7 +336,7 @@ static void dentry_lru_add(struct dentry *dentry) spin_lock(&dcache_lru_lock); list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); dentry->d_sb->s_nr_dentry_unused++; - dentry_stat.nr_unused++; + this_cpu_inc(nr_dentry_unused); spin_unlock(&dcache_lru_lock); } } @@ -322,7 +346,7 @@ static void __dentry_lru_del(struct dentry *dentry) list_del_init(&dentry->d_lru); dentry->d_flags &= ~DCACHE_SHRINK_LIST; dentry->d_sb->s_nr_dentry_unused--; - dentry_stat.nr_unused--; + this_cpu_dec(nr_dentry_unused); } /* @@ -343,7 +367,7 @@ static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list) if (list_empty(&dentry->d_lru)) { list_add_tail(&dentry->d_lru, list); dentry->d_sb->s_nr_dentry_unused++; - dentry_stat.nr_unused++; + this_cpu_inc(nr_dentry_unused); } else { list_move_tail(&dentry->d_lru, list); } -- 2.39.5