On 04/10/2016 20:01, Konstantin Belousov wrote:
> Author: kib
> Date: Tue Oct 4 17:01:24 2016
> New Revision: 306680
> URL: https://svnweb.freebsd.org/changeset/base/306680
> Re-apply r306516 (by cem):
> Reduce the cost of TLB invalidation on x86 by using per-CPU completion flags
> Reduce contention during TLB invalidation operations by using a per-CPU
> completion flag, rather than a single atomically-updated variable.
could this commit cause a problem reported in the below links?
> On a Westmere system (2 sockets x 4 cores x 1 threads), dtrace measurements
> show that smp_tlb_shootdown is about 50% faster with this patch;
> with VTune show that the percentage of time spent in invlrng_single_page on
> interrupt (actually doing invalidation, rather than synchronization)
> from 31% with the old mechanism to 71% with the new one. (Running a basic
> server workload.)
> Submitted by: Anton Rang <rang at acm.org>
> Reviewed by: cem (earlier version)
> Sponsored by: Dell EMC Isilon
> Differential Revision: https://reviews.freebsd.org/D8041
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