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Subject[PATCH] 2.6.9-rc3-mm2 alloc_percpu fix for non-NUMA
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Hi,

alloc_percpu() calls kmem_cache_alloc_node() to allocate memory
on a particular node. But for non-NUMA cases, it doesn't matter
all the memory comes from same node. This patch short-cuts and
calls kmalloc() if its non-NUMA. I hate to add #ifdefs in the
mainline code, but I don't see easy way around.

kmem_cache_alloc_node()allocates a new slab to satisfy allocation
from that node instead of doing it from a partial slab from that node
- which causes fragmentation (with my scsi-debug tests). Thats my
next problem to deal with.

BTW, with this patch size-64 cache is no longer fragmented for
scsi-debug test case.

size-64 76920 76921 64 61 1 : tunables 120 60
8 : slabdata 1261 1261 0

Thanks,
Badari



Signed-off-by: pbadari@us.ibm.com
--- linux-2.6.9-rc3.org/mm/slab.c 2004-10-07 07:55:05.451137928 -0700
+++ linux-2.6.9-rc3/mm/slab.c 2004-10-07 07:55:56.990160360 -0700
@@ -2452,9 +2452,13 @@ void *__alloc_percpu(size_t size, size_t
for (i = 0; i < NR_CPUS; i++) {
if (!cpu_possible(i))
continue;
+#ifdef CONFIG_NUMA
pdata->ptrs[i] = kmem_cache_alloc_node(
kmem_find_general_cachep(size, GFP_KERNEL),
cpu_to_node(i));
+#else
+ pdata->ptrs[i] = kmalloc(size, GFP_KERNEL);
+#endif

if (!pdata->ptrs[i])
goto unwind_oom;
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