Re: [PATCH v5 6/7] x86/tlb: optimizing flush_tlb_mm

[Nick Piggin]

On 15 May 2012 19:18, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> On Tue, 2012-05-15 at 19:15 +1000, Nick Piggin wrote:
>> So this should go to linux-arch...
>>
>> On 15 May 2012 18:55, Alex Shi <alex.shi@xxxxxxxxx> wrote:
>> > Not every flush_tlb_mm execution moment is really need to evacuate all
>> > TLB entries, like in munmap, just few 'invlpg' is better for whole
>> > process performance, since it leaves most of TLB entries for later
>> > accessing.
>> >
>> > This patch is changing flush_tlb_mm(mm) to flush_tlb_mm(mm, start, end)
>> > in cases.
>>
>> What happened with Peter's comment about using flush_tlb_range for this?
>>
>> flush_tlb_mm() API should just stay unchanged AFAIKS.
>>
>> Then you need to work out the best way to give range info to the tlb/mmu gather
>> API. Possibly passing in the rage for that guy is OK, which x86 can
>> then implement
>> as flush range.
>
> Right, most archs that have tlb_flush_range() do range tracking in
> mmu_gather. Our TLB ops fully support that, there's absolutely no need
> to go change the interface for thos.

It could be warranted to change tlb_flush_mmu to a range API to
avoid doing the per-entry tracking which those architectures do?

The callers have range available easily, so ignoring those could be
noop for generic helpers.
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