Messages in this thread | | | Date | Mon, 19 Apr 2021 11:56:30 +0100 | From | Vincent Donnefort <> | Subject | Re: [PATCH 3/3] sched: Use cpu_dying() to fix balance_push vs hotplug-rollback |
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On Thu, Apr 15, 2021 at 03:32:11PM +0100, Valentin Schneider wrote: > On 15/04/21 10:59, Peter Zijlstra wrote: > > Can't make sense of what I did.. I've removed that hunk. Patch now looks > > like this. > > > > Small nit below, but regardless feel free to apply to the whole lot: > Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> > > @VincentD, ISTR you had tested the initial version of this with your fancy > shmancy hotplug rollback stresser. Feel like doing this
I indeed wrote a test to verify all the rollback cases, up and down.
It seems I encounter an intermitent issue while running several iterations of that test ... but I need more time to debug and figure-out where it is blocking.
> > > So instead, make sure balance_push is enabled between > > sched_cpu_deactivate() and sched_cpu_activate() (eg. when > > !cpu_active()), and gate it's utility with cpu_dying(). > > I'd word that "is enabled below sched_cpu_activate()", since > sched_cpu_deactivate() is now out of the picture. > > [...] > > @@ -7639,6 +7639,9 @@ static DEFINE_PER_CPU(struct cpu_stop_wo > > > > /* > > * Ensure we only run per-cpu kthreads once the CPU goes !active. > > + * > > + * This is active/set between sched_cpu_deactivate() / sched_cpu_activate(). > > Ditto > > > + * But only effective when the hotplug motion is down. > > */ > > static void balance_push(struct rq *rq) > > {
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