tree 285dc114754f7a6acd5dde5eac5a628bdd14598e
parent cf3c0a1579eff90195a791c5f464463c1011ef4a
author Linus Torvalds <torvalds@linux-foundation.org> 1418846344 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1418846344 -0800

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>