From owner-freebsd-threads@FreeBSD.ORG  Fri Feb 17 09:37:43 2012
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Date: Fri, 17 Feb 2012 11:37:09 +0200
From: Andriy Gapon <avg@FreeBSD.org>
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To: Julian Elischer <julian@FreeBSD.org>
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Cc: Alexander Kabaev <kan@FreeBSD.org>, threads@FreeBSD.org,
	FreeBSD Stable <freebsd-stable@FreeBSD.org>,
	David Xu <davidxu@FreeBSD.org>, Jung-uk Kim <jkim@FreeBSD.org>
Subject: Re: pthread_cond_timedwait() broken in 9-stable? [possible answer]
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on 17/02/2012 03:55 Julian Elischer said the following:
> 
> kern.timecounter.tick: 1
> kern.timecounter.choice: TSC-low(1000) i8254(0) HPET(950) ACPI-fast(900)
> dummy(-1000000)
> kern.timecounter.hardware: ACPI-fast
> kern.timecounter.stepwarnings: 0
> 
> switching the machine from TSC_low to ACPI-fast  fixes the problem.
> 
> in 8.x it used to default to ACPI
> but I used to switch it to "TSC" to get better performance.
> 
> I wonder why TSC-low is now bad to use..
> maybe the TSCs are not as well sychronised as they were in 8.x?
> maybe the pthreads code didn't get the memo about changing timers?

More useful information that you can provide:
- C-states configuration
- CPU identification

I see that you've already contacted jkim, that's useful too.

-- 
Andriy Gapon