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

From: Peter Zijlstra
Date: Tue May 15 2012 - 09:06:28 EST


On Tue, 2012-05-15 at 20:58 +0800, Luming Yu wrote:
>
>
> Both __native_flush_tlb() and __native_flush_tlb_single(...)
> introduced roughly 1 ns latency to tsc sampling executed in
> stop_machine_context in two logical CPUs

But you have to weight that against the cost of re-population, and
that's the difficult bit, since we have no clue how many tlb entries are
in use by the current cr3.

It might be possible for intel to give us this information, I've asked
for something similar for cachelines.

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