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[PATCH] Use __read_mostly on some hot fs variables

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I discovered on oprofile hunting on a SMP platform that dentry lookups were
slowed down because d_hash_mask, d_hash_shift and dentry_hashtable were in
a cache line that contained inodes_stat.  So each time inodes_stats is
changed by a cpu, other cpus have to refill their cache line.

This patch moves some variables to the __read_mostly section, in order to
avoid false sharing.  RCU dentry lookups can go full speed.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Eric Dumazet
2006-03-26 01:37:24 -08:00
committed by Linus Torvalds
parent 878a9f30d7
commit fa3536cc14
12 changed files with 35 additions and 35 deletions
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4
fs/fcntl.c
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@@ -412,7 +412,7 @@ out:
/* Table to convert sigio signal codes into poll band bitmaps */
static long band_table[NSIGPOLL] = {
static const long band_table[NSIGPOLL] = {
POLLIN | POLLRDNORM, /* POLL_IN */
POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */
POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */
@@ -531,7 +531,7 @@ int send_sigurg(struct fown_struct *fown)
}
static DEFINE_RWLOCK(fasync_lock);
static kmem_cache_t *fasync_cache;
static kmem_cache_t *fasync_cache __read_mostly;
/*
* fasync_helper() is used by some character device drivers (mainly mice)