Messages in this thread |  | | | Date | Tue, 24 Nov 2009 13:28:53 +0200 | | Subject | Re: [PATCH 3/5] slab.c: remove branch hint | | From | Pekka Enberg <> |
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On Tue, Nov 24, 2009 at 1:20 PM, Ingo Molnar <mingo@elte.hu> wrote: > (Pekka Cc:-ed) > > * Tim Blechmann <tim@klingt.org> wrote: > >> branch profiling on my nehalem machine showed 99% incorrect branch hints: >> >> 28459 7678524 99 __cache_alloc_node slab.c >> 3551 >> >> Signed-off-by: Tim Blechmann <tim@klingt.org> >> --- >> mm/slab.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/mm/slab.c b/mm/slab.c >> index f70b326..4125fcd 100644 >> --- a/mm/slab.c >> +++ b/mm/slab.c >> @@ -3548,7 +3548,7 @@ __cache_alloc_node(struct kmem_cache *cachep, >> gfp_t flags, int nodeid, >> slab_irq_save(save_flags, this_cpu); >> this_node = cpu_to_node(this_cpu); >> - if (unlikely(nodeid == -1)) >> + if (nodeid == -1) >> nodeid = this_node; >> if (unlikely(!cachep->nodelists[nodeid])) {
That sounds odd to me. Can you see where the incorrectly predicted calls are coming from? Calling kmem_cache_alloc_node() with node set to -1 most of the time could be a real bug somewhere. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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