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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/block_dev.c
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@ -234,7 +234,7 @@ static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
*/
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
static kmem_cache_t * bdev_cachep;
static kmem_cache_t * bdev_cachep __read_mostly;
static struct inode *bdev_alloc_inode(struct super_block *sb)
{
@ -308,7 +308,7 @@ static struct file_system_type bd_type = {
.kill_sb = kill_anon_super,
};
static struct vfsmount *bd_mnt;
static struct vfsmount *bd_mnt __read_mostly;
struct super_block *blockdev_superblock;
void __init bdev_cache_init(void)