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SubjectRemove constructor from buffer_head
Performance tests show a slight improvements in netperf (not a
strong case for a performance improvement but removing the
constructor has definitely no negative impact so why keep
this around?).

TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost (127.0.0.1) port 0 AF_INET
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec

Before:
87380 16384 16384 10.01 6026.04
87380 16384 16384 10.01 5992.17
87380 16384 16384 10.01 6071.23

After:
87380 16384 16384 10.01 6090.20
87380 16384 16384 10.01 6078.3
87380 16384 16384 10.00 6013.52


Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
fs/buffer.c | 22 ++++------------------
1 file changed, 4 insertions(+), 18 deletions(-)
Index: slub/fs/buffer.c
===================================================================
--- slub.orig/fs/buffer.c 2007-05-03 19:17:09.000000000 -0700
+++ slub/fs/buffer.c 2007-05-03 19:57:30.000000000 -0700
@@ -2907,9 +2907,10 @@ 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,
+ struct buffer_head *ret = kmem_cache_zalloc(bh_cachep,
set_migrateflags(gfp_flags, __GFP_RECLAIMABLE));
if (ret) {
+ INIT_LIST_HEAD(&ret->b_assoc_buffers);
get_cpu_var(bh_accounting).nr++;
recalc_bh_state();
put_cpu_var(bh_accounting);
@@ -2928,17 +2929,6 @@ void free_buffer_head(struct buffer_head
}
EXPORT_SYMBOL(free_buffer_head);

-static void
-init_buffer_head(void *data, struct kmem_cache *cachep, unsigned long flags)
-{
- if (flags & SLAB_CTOR_CONSTRUCTOR) {
- struct buffer_head * bh = (struct buffer_head *)data;
-
- memset(bh, 0, sizeof(*bh));
- INIT_LIST_HEAD(&bh->b_assoc_buffers);
- }
-}
-
static void buffer_exit_cpu(int cpu)
{
int i;
@@ -2965,12 +2955,8 @@ void __init buffer_init(void)
{
int nrpages;

- bh_cachep = kmem_cache_create("buffer_head",
- sizeof(struct buffer_head), 0,
- (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
- SLAB_MEM_SPREAD),
- init_buffer_head,
- NULL);
+ bh_cachep = KMEM_CACHE(buffer_head,
+ SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);

/*
* Limit the bh occupancy to 10% of ZONE_NORMAL
-
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