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SubjectRe: [PATCH] reduce fragmentation due to kmem_cache_alloc_node

This patch seems to work fine on my AMD machine.
I tested your patch on 2.6.9-rc2-mm3.

It seemed to have fixed fragmentation problem I was
observing, but I don't think it fixed the problem
completely. I still see some fragmentation, with
repeated tests of scsi-debug, but it could be due
to the test. I will collect more numbers..


On Sat, 2004-10-09 at 13:37, Manfred Spraul wrote:
> Hi Andrew,
> attached is a patch that fixes the fragmentation that Badri noticed with
> kmem_cache_alloc_node. Could you add it to the mm tree? The patch is
> against 2.6.9-rc3-mm3.
> Description:
> kmem_cache_alloc_node tries to allocate memory from a given node. The
> current implementation contains two bugs:
> - the node aware code was used even for !CONFIG_NUMA systems. Fix:
> inline function that redefines kmem_cache_alloc_node as kmem_cache_alloc
> - the code always allocated a new slab for each new allocation. This
> caused severe fragmentation. Fix: walk the slabp lists and search for a
> matching page instead of allocating a new page.
> - the patch also adds a new statistics field for node-local allocs. They
> should be rare - the codepath is quite slow, especially compared to the
> normal kmem_cache_alloc.
> Badri: Could you test it?
> Andrew, could you add the patch to the next -mm kernel? I'm running it
> right now, no obvious problems.
> Signed-Off-By: Manfred Spraul <>
> ______________________________________________________________________

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