linux-kernel - Re: [patch] fix the softlockup watchdog to actually work

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Message-ID: <p73ejiwsaq9.fsf@bingen.suse.de>
Date:	25 Jul 2007 18:34:54 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Jeremy Fitzhardinge <jeremy@...p.org>,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	stable@...nel.org, Greg KH <greg@...ah.com>,
	Chris Wright <chrisw@...s-sol.org>
Subject: Re: [patch] fix the softlockup watchdog to actually work

Andrew Morton <akpm@...ux-foundation.org> writes:
> 
> One possibility is that sched_clock() is bollixed and (say) it's returning
> a 32-bit value.  That'll cause the softlockup logic to get a bit sick when
> time wraps.

FYI, The current ff x86 sched_clock() [which you likely have, it's not
mainline] tends to warp backwards by 80-90ms during cpu freq changes
on AMD on one of my test systems. I haven't tracked down why it does
that yet. Intel or systems with no cpufreq or cpufreq not changing
frequencies regularly are not affected

-Andi
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