Re: [PATCH 4/6] x86: mm: trace tlb flushes

[Rik van Riel]

On 04/21/2014 02:24 PM, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> 
> We don't have any good way to figure out what kinds of flushes
> are being attempted.  Right now, we can try to use the vm
> counters, but those only tell us what we actually did with the
> hardware (one-by-one vs full) and don't tell us what was actually
> _requested_.
> 
> This allows us to select out "interesting" TLB flushes that we
> might want to optimize (like the ranged ones) and ignore the ones
> that we have very little control over (the ones at context
> switch).
> 
> Also, since we have a pair of tracepoint calls in
> flush_tlb_mm_range(), we can time the deltas between them to make
> sure that we got the "invlpg vs. global flush" balance correct in
> practice.
> 
> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

Acked-by: Rik van Riel <riel@xxxxxxxxxx>


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