[patch 0/2] softlockup watchdog improvements

From: Jeremy Fitzhardinge
Date: Tue Mar 27 2007 - 01:49:33 EST


Here's couple of patches to improve the softlockup watchdog.

The first changes the softlockup timer from using jiffies to sched_clock()
as a timebase. Xen and VMI implement sched_clock() as counting unstolen
time, so time stolen by the hypervisor won't cause the watchdog to bite.

The second adds per-cpu enable flags for the watchdog timer. This allows
the timer to be disabled when the CPU goes into a (potentially unbounded)
tickless sleep.

I know this conflicts with
fix-bogus-softlockup-warning-with-sysrq-t.patch in -mm2. I think that
patch incorrectly changes the behaviour of the softlockup watchdog,
and a better solution is to temporarily disable the watchdog while
doing something known to be cpu-consuming, like a long sysreq output.

J
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