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Date: Wed, 12 Oct 2016 16:45:50 +0300
From: Konstantin Belousov <kostikbel@gmail.com>
To: Andriy Gapon <avg@FreeBSD.org>
Cc: src-committers@FreeBSD.org, svn-src-all@FreeBSD.org,
 svn-src-head@FreeBSD.org
Subject: Re: svn commit: r306680 - in head/sys: amd64/amd64 amd64/include
 i386/include x86/include x86/x86
Message-ID: <20161012134550.GX68202@kib.kiev.ua>
References: <201610041701.u94H1OK3061119@repo.freebsd.org>
 <425655dd-ba13-8944-0f31-b1ad6666d90a@FreeBSD.org>
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On Wed, Oct 12, 2016 at 04:25:00PM +0300, Andriy Gapon wrote:
> 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

If I am reading the report right, the problem appears on the
11.0-RELEASE system. The patch you reference was only applied to HEAD a
week ago and was not merged even to stable/11.

The examination must start with backtracing the thread which owns the
smp_ipi_mtx (shown on the screenshot).