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Message-Id: <1234890096.11511.6.camel@penberg-laptop>
Date: Tue, 17 Feb 2009 19:01:36 +0200
From: Pekka Enberg <penberg@...helsinki.fi>
To: Christoph Lameter <cl@...ux-foundation.org>
Cc: Mel Gorman <mel@....ul.ie>, Nick Piggin <nickpiggin@...oo.com.au>,
Nick Piggin <npiggin@...e.de>,
Linux Memory Management List <linux-mm@...ck.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Lin Ming <ming.m.lin@...el.com>,
"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
Subject: Re: [patch] SLQB slab allocator (try 2)
Hi Christoph,
On Mon, 16 Feb 2009, Pekka Enberg wrote:
> > Btw, Yanmin, do you have access to the tests Mel is running (especially the
> > ones where slub-rvrt seems to do worse)? Can you see this kind of regression?
> > The results make we wonder whether we should avoid reverting all of the page
> > allocator pass-through and just add a kmalloc cache for 8K allocations. Or not
> > address the netperf regression at all. Double-hmm.
On Tue, 2009-02-17 at 11:20 -0500, Christoph Lameter wrote:
> Going to 8k for the limit beyond we pass through to the page allocator may
> be the simplest and best solution. Someone please work on the page
> allocator...
Yeah. Something like this totally untested patch, perhaps?
Pekka
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 2f5c16b..e93cb3d 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -201,6 +201,13 @@ static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
#define SLUB_DMA (__force gfp_t)0
#endif
+/*
+ * The maximum allocation size that will be satisfied by the slab allocator for
+ * kmalloc(). Requests that exceed this limit are passed directly to the page
+ * allocator.
+ */
+#define SLAB_LIMIT (8 * 1024)
+
void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
void *__kmalloc(size_t size, gfp_t flags);
@@ -212,7 +219,7 @@ static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
static __always_inline void *kmalloc(size_t size, gfp_t flags)
{
if (__builtin_constant_p(size)) {
- if (size > PAGE_SIZE)
+ if (size > SLAB_LIMIT)
return kmalloc_large(size, flags);
if (!(flags & SLUB_DMA)) {
@@ -234,7 +241,7 @@ void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
if (__builtin_constant_p(size) &&
- size <= PAGE_SIZE && !(flags & SLUB_DMA)) {
+ size <= SLAB_LIMIT && !(flags & SLUB_DMA)) {
struct kmem_cache *s = kmalloc_slab(size);
if (!s)
diff --git a/mm/slub.c b/mm/slub.c
index 0280eee..a324188 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2658,7 +2658,7 @@ void *__kmalloc(size_t size, gfp_t flags)
{
struct kmem_cache *s;
- if (unlikely(size > PAGE_SIZE))
+ if (unlikely(size > SLAB_LIMIT))
return kmalloc_large(size, flags);
s = get_slab(size, flags);
@@ -2686,7 +2686,7 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node)
{
struct kmem_cache *s;
- if (unlikely(size > PAGE_SIZE))
+ if (unlikely(size > SLAB_LIMIT))
return kmalloc_large_node(size, flags, node);
s = get_slab(size, flags);
@@ -3223,7 +3223,7 @@ void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, unsigned long caller)
{
struct kmem_cache *s;
- if (unlikely(size > PAGE_SIZE))
+ if (unlikely(size > SLAB_LIMIT))
return kmalloc_large(size, gfpflags);
s = get_slab(size, gfpflags);
@@ -3239,7 +3239,7 @@ void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
{
struct kmem_cache *s;
- if (unlikely(size > PAGE_SIZE))
+ if (unlikely(size > SLAB_LIMIT))
return kmalloc_large_node(size, gfpflags, node);
s = get_slab(size, gfpflags);
--
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