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Subject[PATCH 1/3] slub: set a criteria for slub node partial adding
Date
From: Alex Shi <alexs@intel.com>

Times performance regression were due to slub add to node partial head
or tail. That inspired me to do tunning on the node partial adding, to
set a criteria for head or tail position selection when do partial
adding.
My experiment show, when used objects is less than 1/4 total objects
of slub performance will get about 1.5% improvement on netperf loopback
testing with 2048 clients, wherever on our 4 or 2 sockets platforms,
includes sandbridge or core2.

Signed-off-by: Alex Shi <alex.shi@intel.com>
---
mm/slub.c | 18 ++++++++----------
1 files changed, 8 insertions(+), 10 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index ed3334d..c419e80 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1461,14 +1461,13 @@ static void discard_slab(struct kmem_cache *s, struct page *page)
*
* list_lock must be held.
*/
-static inline void add_partial(struct kmem_cache_node *n,
- struct page *page, int tail)
+static inline void add_partial(struct kmem_cache_node *n, struct page *page)
{
n->nr_partial++;
- if (tail == DEACTIVATE_TO_TAIL)
- list_add_tail(&page->lru, &n->partial);
- else
+ if (page->inuse <= page->objects / 4)
list_add(&page->lru, &n->partial);
+ else
+ list_add_tail(&page->lru, &n->partial);
}

/*
@@ -1829,7 +1828,7 @@ redo:

if (m == M_PARTIAL) {

- add_partial(n, page, tail);
+ add_partial(n, page);
stat(s, tail);

} else if (m == M_FULL) {
@@ -1904,8 +1903,7 @@ static void unfreeze_partials(struct kmem_cache *s)
if (l == M_PARTIAL)
remove_partial(n, page);
else
- add_partial(n, page,
- DEACTIVATE_TO_TAIL);
+ add_partial(n, page);

l = m;
}
@@ -2476,7 +2474,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page,
*/
if (unlikely(!prior)) {
remove_full(s, page);
- add_partial(n, page, DEACTIVATE_TO_TAIL);
+ add_partial(n, page);
stat(s, FREE_ADD_PARTIAL);
}
}
@@ -2793,7 +2791,7 @@ static void early_kmem_cache_node_alloc(int node)
init_kmem_cache_node(n, kmem_cache_node);
inc_slabs_node(kmem_cache_node, node, page->objects);

- add_partial(n, page, DEACTIVATE_TO_HEAD);
+ add_partial(n, page);
}

static void free_kmem_cache_nodes(struct kmem_cache *s)
--
1.7.0.1


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