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Date: Thu, 16 Feb 2012 17:55:58 -0800
From: 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>
Subject: Re: pthread_cond_timedwait() broken in 9-stable? [possible answer]
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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?