Messages in this thread | | | Date | Tue, 6 Sep 2011 15:03:27 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 13/32] nohz: Adaptive tick stop and restart on nohz cpuset |
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On Mon, Aug 29, 2011 at 05:25:36PM +0200, Peter Zijlstra wrote: > On Mon, 2011-08-15 at 17:52 +0200, Frederic Weisbecker wrote: > > When a CPU is included in a nohz cpuset, try to switch > > it to nohz mode from the timer interrupt if it is the > > only non-idle task running. > > > > Then restart the tick if necessary from the wakeup path > > if we are enqueuing a second task while the timer is stopped, > > so that the scheduler tick is rearmed. > > Shouldn't you first put the syscall hooks in place before allowing the > tick to be switched off? It seems this patch is somewhat too early in > the series.
I don't think it's necessary, that part doesn't depend on userspace hooks. The whole thing is enabled very late anyway.
> > This assumes we are using TTWU_QUEUE sched feature so I need > > to handle the off case (or actually not handle it but properly), > > because we need the adaptive tick restart and what will come > > along in further patches to be done locally and before the new > > task ever gets scheduled. > > We could certainly remove that feature flag and always use it, it was > mostly a transition debug switch in case something didn't work or > performance issues were found due to this.
Ok, good.
> > I also need to look at the ARCH_WANT_INTERRUPTS_ON_CTXW case > > and the remote wakeups. > > Well, ideally we'd simply get rid of that, rmk has some preliminary > patches in that direction.
Great!
Thanks.
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