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| author | Richard Kennedy <richard@rsk.demon.co.uk> | 2010-03-10 15:20:33 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-03-12 15:52:27 -0800 |
| commit | 019b4d123aa7b9fc135b532e021cfde85db7665d (patch) | |
| tree | 91edbae535136417bc1277dd2c40d98c7ea7ec8f | |
| parent | 03affdef4fc85e416e3862abb0aa549c6034cdd0 (diff) | |
| download | linux-019b4d123aa7b9fc135b532e021cfde85db7665d.tar.gz linux-019b4d123aa7b9fc135b532e021cfde85db7665d.tar.bz2 linux-019b4d123aa7b9fc135b532e021cfde85db7665d.zip | |
fs: buffer_head: remove kmem_cache constructor to reduce memory usage under slub
When using slub, having a kmem_cache constructor forces slub to add a free
pointer to the size of the cached object, which can have a significant
impact to the number of small objects that can fit into a slab.
As buffer_head is relatively small and we can have large numbers of them,
removing the constructor is a definite win.
On x86_64 removing the constructor gives me 39 objects/slab, 3 more than
without the patch. And on x86_32 73 objects/slab, which is 9 more.
As alloc_buffer_head() already initializes each new object there is very
little difference in actual code run.
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/buffer.c | 13 |
1 files changed, 2 insertions, 11 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index 6fa530256bfd..bc3212e0cef9 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -3265,7 +3265,7 @@ static void recalc_bh_state(void) struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) { - struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags); + struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); if (ret) { INIT_LIST_HEAD(&ret->b_assoc_buffers); get_cpu_var(bh_accounting).nr++; @@ -3352,15 +3352,6 @@ int bh_submit_read(struct buffer_head *bh) } EXPORT_SYMBOL(bh_submit_read); -static void -init_buffer_head(void *data) -{ - struct buffer_head *bh = data; - - memset(bh, 0, sizeof(*bh)); - INIT_LIST_HEAD(&bh->b_assoc_buffers); -} - void __init buffer_init(void) { int nrpages; @@ -3369,7 +3360,7 @@ void __init buffer_init(void) sizeof(struct buffer_head), 0, (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| SLAB_MEM_SPREAD), - init_buffer_head); + NULL); /* * Limit the bh occupancy to 10% of ZONE_NORMAL |