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Commit b2455396 authored by Paul Jackson's avatar Paul Jackson Committed by Linus Torvalds
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[PATCH] cpuset: memory_spread_slab drop useless PF_SPREAD_PAGE check 



The hook in the slab cache allocation path to handle cpuset memory
spreading for tasks in cpusets with 'memory_spread_slab' enabled has a
modest performance bug.  The hook calls into the memory spreading handler
alternate_node_alloc() if either of 'memory_spread_slab' or
'memory_spread_page' is enabled, even though the handler does nothing
(albeit harmlessly) for the page case

Fix - drop PF_SPREAD_PAGE from the set of flag bits that are used to
trigger a call to alternate_node_alloc().

The page case is handled by separate hooks -- see the calls conditioned on
cpuset_do_page_mem_spread() in mm/filemap.c

Signed-off-by: default avatarPaul Jackson <pj@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 151a4420

mm/slab.c

+2 −3
Original line number Diff line number Diff line
@@ -2809,8 +2809,7 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags) 
	struct array_cache *ac;



#ifdef CONFIG_NUMA

	if (unlikely(current->flags & (PF_SPREAD_PAGE | PF_SPREAD_SLAB |

							PF_MEMPOLICY))) {

	if (unlikely(current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY))) {

		objp = alternate_node_alloc(cachep, flags);

		if (objp != NULL)

			return objp;
@@ -2849,7 +2848,7 @@ static __always_inline void *__cache_alloc(struct kmem_cache *cachep, 


#ifdef CONFIG_NUMA

/*

 * Try allocating on another node if PF_SPREAD_PAGE|PF_SPREAD_SLAB|PF_MEMPOLICY.

 * Try allocating on another node if PF_SPREAD_SLAB|PF_MEMPOLICY.

 *

 * If we are in_interrupt, then process context, including cpusets and

 * mempolicy, may not apply and should not be used for allocation policy.