powerpc/mm/radix: Improve TLB/PWC flushes

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At the moment we have to rather sub-optimal flushing behaviours:

 - flush_tlb_mm() will flush the PWC which is unnecessary (for example
   when doing a fork)

 - A large unmap will call flush_tlb_pwc() multiple times causing us
   to perform that fairly expensive operation repeatedly. This happens
   often in batches of 3 on every new process.

So we change flush_tlb_mm() to only flush the TLB, and we use the
existing "need_flush_all" flag in struct mmu_gather to indicate
that the PWC needs flushing.

Unfortunately, flush_tlb_range() still needs to do a full flush
for now as it's used by the THP collapsing. We will fix that later.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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Benjamin Herrenschmidt 2017-07-19 14:49:05 +10:00 • committed by Michael Ellerman

parent 5ce5fe14ed

commit a46cc7a90f

2 changed files with 28 additions and 42 deletions

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4

arch/powerpc/include/asm/book3s/64/tlbflush-radix.h

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84

arch/powerpc/mm/tlb-radix.c

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