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authorLinus Torvalds <torvalds@linux-foundation.org>2014-12-17 20:59:04 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-17 20:59:04 +0100
commitf045bbb9fa1bf6f507ad4de12d4e3471d8f672f1 (patch)
tree285dc114754f7a6acd5dde5eac5a628bdd14598e /kernel/groups.c
parentx86: mm: fix VM_FAULT_RETRY handling (diff)
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mmu_gather: fix over-eager tlb_flush_mmu_free() calling
Dave Hansen reports that commit fb7332a9fedf ("mmu_gather: move minimal range calculations into generic code") caused a performance problem: "tlb_finish_mmu() goes up about 9x in the profiles (~0.4%->3.6%) and tlb_flush_mmu_free() takes about 3.1% of CPU time with the patch applied, but does not show up at all on the commit before" and the reason is that Will moved the test for whether we need to flush from tlb_flush_mmu() into tlb_flush_mmu_tlbonly(). But that meant that tlb_flush_mmu_free() basically lost that check. Move it back into tlb_flush_mmu() where it belongs, so that it covers both tlb_flush_mmu_tlbonly() _and_ tlb_flush_mmu_free(). Reported-and-tested-by: Dave Hansen <dave@sr71.net> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/groups.c')
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