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Date: Thu, 12 May 2011 03:55:22 -0700
From: Stanislav Sedov <stas@FreeBSD.org>
To: Andriy Gapon <avg@FreeBSD.org>
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Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org,
	src-committers@FreeBSD.org, Jung-uk Kim <jkim@FreeBSD.org>
Subject: Re: svn commit: r221703 - in head/sys: amd64/include i386/include
 x86/isa x86/x86
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On Thu, 12 May 2011 13:43:58 +0300
Andriy Gapon <avg@FreeBSD.org> mentioned:

> 
> Theory:
> - smp_rv_waiters[2] becomes equal to smp_rv_ncpus
> - [at least] one slave CPU is still in the last call to cpu_spinwait() in
> smp_rendezvous_action()
> - master CPU notices that the condition is true, exits smp_rendezvous_cpus() and
> calls it again
> - the slave CPU is still in spinwait
> - the master CPU resets smp_rv_waiters[2] to zero
> - the slave CPU exits spinwait, see smp_rv_waiters[2] with zero value
> - endless loop
> 

That might explain it.
Do you have a patch for me to try?

Thanks!

-- 
Stanislav Sedov
ST4096-RIPE

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