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
> 
> Log:
>   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.

Kostik,

could this commit cause a problem reported in the below links?
https://bz-attachments.freebsd.org/attachment.cgi?id=175614
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=213371

>   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; 
> observations
>   with VTune show that the percentage of time spent in invlrng_single_page on 
> an
>   interrupt (actually doing invalidation, rather than synchronization) 
> increases
>   from 31% with the old mechanism to 71% with the new one.  (Running a basic 
> file
>   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

-- 
Andriy Gapon
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