lkml.org 
[lkml]   [2010]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] hangcheck-timer is broken on x86
    On Sat, Mar 27, 2010 at 06:51:01PM -0400, Yury Polyanskiy wrote:
    > >        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.
    >
    > Joel, what I am saying is exactly the opposite: it is totally ok to
    > suspend-resume with hangcheck-timer (jiffies are stopped and so is
    > getrawmonotonic() when system suspended).

    Nope. The point of hangcheck-timer is that it reboots should
    the system not be running for a certain amountof time. If
    suspend-resume is allowed, a system can resume after days and think it
    wasn't more than a second. hangcheck-timer will not know to reboot.

    > >        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?
    >
    > Of course, getrawmonotonic accounts for cpufreq changes (see
    > arch/x86/kernel/tsc.c:time_cpufreq_notifier()).

    Excellent! That's a definite improvement over raw get_cycles().

    Joel

    --

    Life's Little Instruction Book #182

    "Be romantic."

    Joel Becker
    Principal Software Developer
    Oracle
    E-mail: joel.becker@oracle.com
    Phone: (650) 506-8127
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2010-03-28 00:39    [W:0.043 / U:31.684 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site