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mm, x86: Account for TLB flushes only when debugging

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Bisection between 3.11 and 3.12 fingered commit 9824cf97 ("mm:
vmstats: tlb flush counters") to cause overhead problems.

The counters are undeniably useful but how often do we really
need to debug TLB flush related issues?  It does not justify
taking the penalty everywhere so make it a debugging option.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-XzxjntugxuwpxXhcrxqqh53b@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Mel Gorman
2014-01-21 14:33:16 -08:00
committed by Ingo Molnar
parent 2993ae3305
commit ec65993443
6 changed files with 26 additions and 14 deletions
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4
arch/x86/kernel/cpu/mtrr/generic.c
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@@ -683,7 +683,7 @@ static void prepare_set(void) __acquires(set_atomicity_lock)
}
/* Flush all TLBs via a mov %cr3, %reg; mov %reg, %cr3 */
count_vm_event(NR_TLB_LOCAL_FLUSH_ALL);
count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
__flush_tlb();
/* Save MTRR state */
@@ -697,7 +697,7 @@ static void prepare_set(void) __acquires(set_atomicity_lock)
static void post_set(void) __releases(set_atomicity_lock)
{
/* Flush TLBs (no need to flush caches - they are disabled) */
count_vm_event(NR_TLB_LOCAL_FLUSH_ALL);
count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
__flush_tlb();
/* Intel (P6) standard MTRRs */