Re: [PATCH] hangcheck-timer is broken on x86

Joel Becker
2010-03-27T22:04:35Z

On Fri, Mar 26, 2010 at 10:02:59PM -0400, Yury Polyanskiy wrote:
> Joel, just realized there is a slight mistake in what I said before.
> getrawmonotonic() is a refined jiffies (and actually resolves to
> get_cycles() on my system in the end). Thus it doesn't count while in
> suspend. However, jiffies-based timers (aka timer-wheel) are also
> stopped while in suspend. So getrawmonotonic() is the right call to
> check the precision of the jiffies-based timer (i.e. you dont need to
> make a correction by calling monotonic_to_bootbased()).

It's OK to tell hangcheck-timer users that suspend is not
allowed. After all, you're running something that you don't want to see
hang.
Is there a clock in the system that is a true wallclock? I'm
guessing, since getrawmonotonic() is get_cycles() based, that it doesn't
provide accurate time in the face of cpufreq changes. Is that true?

Joel

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Life's Little Instruction Book #497

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Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127