Currently slub applies NUMA policies per allocated slab page. Change
that to apply memory policies for each individual object allocated.
F.e. before this patch MPOL_INTERLEAVE would return objects from the
same slab page until a new slab page was allocated. Now an object
from a different page is taken for each allocation.
This increases the overhead of the fastpath under NUMA.
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
---
mm/slub.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2011-04-15 12:54:42.000000000 -0500
+++ linux-2.6/mm/slub.c 2011-04-15 13:11:25.000000000 -0500
@@ -1887,6 +1887,21 @@ debug:
goto unlock_out;
}
+static __always_inline int alternate_slab_node(struct kmem_cache *s,
+ gfp_t flags, int node)
+{
+#ifdef CONFIG_NUMA
+ if (unlikely(node == NUMA_NO_NODE &&
+ !(flags & __GFP_THISNODE) &&
+ !in_interrupt())) {
+ if ((s->flags & SLAB_MEM_SPREAD) && cpuset_do_slab_mem_spread())
+ node = cpuset_slab_spread_node();
+ else if (current->mempolicy)
+ node = slab_node(current->mempolicy);
+ }
+#endif
+ return node;
+}
/*
* Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
* have the fastpath folded into their functions. So no function call
@@ -1911,6 +1926,7 @@ static __always_inline void *slab_alloc(
if (slab_pre_alloc_hook(s, gfpflags))
return NULL;
+ node = alternate_slab_node(s, gfpflags, node);
#ifndef CONFIG_CMPXCHG_LOCAL
local_irq_save(flags);
#else
--
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