Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=42a9fdbb12ac6c027b4b91ab9b5a60aa3a834489
Commit: 42a9fdbb12ac6c027b4b91ab9b5a60aa3a834489
Parent: 4c93c355d5d563f300df7e61ef753d7a064411e9
Author: Christoph Lameter <[EMAIL PROTECTED]>
AuthorDate: Tue Oct 16 01:26:09 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Oct 16 09:43:01 2007 -0700
SLUB: Optimize cacheline use for zeroing
We touch a cacheline in the kmem_cache structure for zeroing to get the
size. However, the hot paths in slab_alloc and slab_free do not reference
any other fields in kmem_cache, so we may have to just bring in the
cacheline for this one access.
Add a new field to kmem_cache_cpu that contains the object size. That
cacheline must already be used in the hotpaths. So we save one cacheline
on every slab_alloc if we zero.
We need to update the kmem_cache_cpu object size if an aliasing operation
changes the objsize of an non debug slab.
Signed-off-by: Christoph Lameter <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
include/linux/slub_def.h | 1 +
mm/slub.c | 14 ++++++++++++--
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index f74716b..d65159d 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -16,6 +16,7 @@ struct kmem_cache_cpu {
struct page *page;
int node;
unsigned int offset;
+ unsigned int objsize;
};
struct kmem_cache_node {
diff --git a/mm/slub.c b/mm/slub.c
index 6d4346b..1d48f38 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1576,7 +1576,7 @@ static void __always_inline *slab_alloc(struct kmem_cache
*s,
local_irq_restore(flags);
if (unlikely((gfpflags & __GFP_ZERO) && object))
- memset(object, 0, s->objsize);
+ memset(object, 0, c->objsize);
return object;
}
@@ -1858,8 +1858,9 @@ static void init_kmem_cache_cpu(struct kmem_cache *s,
{
c->page = NULL;
c->freelist = NULL;
- c->offset = s->offset / sizeof(void *);
c->node = 0;
+ c->offset = s->offset / sizeof(void *);
+ c->objsize = s->objsize;
}
static void init_kmem_cache_node(struct kmem_cache_node *n)
@@ -2852,12 +2853,21 @@ struct kmem_cache *kmem_cache_create(const char *name,
size_t size,
down_write(&slub_lock);
s = find_mergeable(size, align, flags, name, ctor);
if (s) {
+ int cpu;
+
s->refcount++;
/*
* Adjust the object sizes so that we clear
* the complete object on kzalloc.
*/
s->objsize = max(s->objsize, (int)size);
+
+ /*
+ * And then we need to update the object size in the
+ * per cpu structures
+ */
+ for_each_online_cpu(cpu)
+ get_cpu_slab(s, cpu)->objsize = s->objsize;
s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
up_write(&slub_lock);
if (sysfs_slab_alias(s, name))
-
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