Messages in this thread | | | Subject | Re: [PATCH v4 00/10] sched/fair: rework the CFS load balance | From | Valentin Schneider <> | Date | Wed, 30 Oct 2019 18:25:09 +0100 |
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On 30/10/2019 18:19, Phil Auld wrote: >> Well from the code nobody but us (asymmetric capacity systems) set >> SD_BALANCE_WAKE. I was however curious if there were some folks who set it >> with out of tree code for some reason. >> >> As Dietmar said, not having SD_BALANCE_WAKE means you'll never go through >> the slow path on wakeups, because there is no domain with SD_BALANCE_WAKE for >> the domain loop to find. Depending on your topology you most likely will >> go through it on fork or exec though. >> >> IOW wake_wide() is not really widening the wakeup scan on wakeups using >> mainline topology code (disregarding asymmetric capacity systems), which >> sounds a bit... off. > > Thanks. It's not currently set. I'll set it and re-run to see if it makes > a difference. >
Note that it might do more harm than good, it's not set in the default topology because it's too aggressive, see
182a85f8a119 ("sched: Disable wakeup balancing")
> > However, I'm not sure why it would be making a difference for only the cgroup > case. If this is causing issues I'd expect it to effect both runs. > > In general I think these threads want to wake up the last cpu they were on. > And given there are fewer cpu bound tasks that CPUs that wake cpu should, > more often than not, be idle. > > > Cheers, > Phil > > >
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