Messages in this thread | | | Date | Fri, 13 Jun 2014 18:21:32 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH] rcu: Only pin GP kthread when full dynticks is actually used |
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On Fri, Jun 13, 2014 at 09:16:30AM -0700, Paul E. McKenney wrote: > > Is it because we have dynticks CPUs staying too long in the kernel without > > taking any quiescent states? Are we perhaps missing some rcu_user_enter() or > > things? > > Sort of the former, but combined with the fact that in-kernel CPUs still > need scheduling-clock interrupts for RCU to make progress. I could > move this to RCU's context-switch hook, but that could be very bad for > workloads that do lots of context switching.
Or I can restart the tick if the CPU stays in the kernel for too long without a tick. I think that's what we were doing before but we removed that because we never implemented it correctly (we sent scheduler IPI that did nothing...)
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