Commit b2455396 authored Mar 24, 2006 by Paul Jackson Committed by Linus Torvalds Mar 24, 2006

[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: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus 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.

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