Messages in this thread | | | Date | Wed, 15 May 2013 13:50:17 -0400 | From | Don Zickus <> | Subject | Re: [PATCH 1/2] nohz: Disable LOCKUP_DETECTOR when NO_HZ_FULL is enabled |
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On Wed, May 15, 2013 at 07:11:53PM +0200, Peter Zijlstra wrote: > On Wed, May 15, 2013 at 06:59:15PM +0200, Peter Zijlstra wrote: > > On Wed, May 15, 2013 at 11:27:02AM -0400, Steven Rostedt wrote: > > > Right now perf requires a tick, not sure exactly why, but you can look > > > at the code in perf_event_task_tick(). Thus if NO_HZ_FULL sees that a > > > perf tick is pending, it won't disable ticks. Unfortunately, the > > > watchdogs, both NMI and soft lockup, use the perf infrastructure to > > > trigger NMIs or interrupts. This adds a perf element on the rotate list > > > and keeps NO_HZ_FULL from *ever* activating. > > > > > > > Hmm.. Stephane had a bunch of patches converting the rotation thing to > > an hrtimer. I seem to have forgotten what happened to them but I can't > > seem to find them merged. > > > > I'll go look. > > > > That leaves the frequency stuff, but the watchdog doesn't use that. > > > > At which point we could run the watchdog without perf_event_task_tick(). > > Found them: > > 1364991694-5876-1-git-send-email-eranian@google.com > > Looks like they were stuck in my inbox and never applied, so I just did. > They should appear in tip soonish.
That was easy. Next problem! :-p
Thanks Peter!
Cheers, Don
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