Messages in this thread | | | Date | Wed, 15 May 2013 18:59:15 +0200 | From | Peter Zijlstra <> | 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 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(). >
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