[PATCH 11/14] mm: Micro-optimise slab to avoid a function call

From: Mel Gorman
Date: Thu Jun 09 2011 - 04:04:37 EST


Getting and putting objects in SLAB currently requires a function call
but the bulk of the work is related to PFMEMALLOC reserves which are
only consumed when network-backed storage is critical. Use an inline
function to determine if the function call is required.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
mm/slab.c | 28 ++++++++++++++++++++++++++--
1 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 708da2f..3f49768 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -117,6 +117,8 @@
#include <linux/memory.h>
#include <linux/prefetch.h>

+#include <net/sock.h>
+
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
@@ -945,7 +947,7 @@ static void check_ac_pfmemalloc(struct kmem_cache *cachep,
ac->pfmemalloc = false;
}

-static void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
+static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
gfp_t flags, bool force_refill)
{
int i;
@@ -992,7 +994,20 @@ static void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
return objp;
}

-static void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+static inline void *ac_get_obj(struct kmem_cache *cachep,
+ struct array_cache *ac, gfp_t flags, bool force_refill)
+{
+ void *objp;
+
+ if (unlikely(sk_memalloc_socks()))
+ objp = __ac_get_obj(cachep, ac, flags, force_refill);
+ else
+ objp = ac->entry[--ac->avail];
+
+ return objp;
+}
+
+static void *__ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
void *objp)
{
struct slab *slabp;
@@ -1005,6 +1020,15 @@ static void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
set_obj_pfmemalloc(&objp);
}

+ return objp;
+}
+
+static inline void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+ void *objp)
+{
+ if (unlikely(sk_memalloc_socks()))
+ objp = __ac_put_obj(cachep, ac, objp);
+
ac->entry[ac->avail++] = objp;
}

--
1.7.3.4

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