Messages in this thread | | | Date | Sat, 9 Apr 2022 19:10:36 +0100 | From | Qais Yousef <> | Subject | Re: [PATCH 0/6] Add latency_nice priority |
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On 04/09/22 13:28, Steven Rostedt wrote: > On Sat, 9 Apr 2022 18:08:41 +0100 > Qais Yousef <qais.yousef@arm.com> wrote: > > > One other corner case to consider if you're working on next version is what > > should happen when there are multiple tasks of the same priority on the rq. RT > > scheduler will push/pull tasks to ensure the task will get to run ASAP if > > there's another cpu at lower priority is available. Seems a lot of complexity > > to add to CFS, but at the same time if 2 important tasks require low latency > > are on the same rq, one of them will suffer without introducing the ability to > > migrate one of them where it can get to run sooner. > > Instead of having the greedy algorithm of the RT push/pull logic, how > hard would it be to have the load balancer know of these tasks, and try > to keep them on different CPUs? When two are queued on the same CPU,
Oh yeah I didn't think we need to replicate push/pull. Load balancer will need to know about it when it moves task so that it avoids placing two of these asks on the same cpu.
> could it be possible to just trigger load balancing and let it do the > work?
I think the other part will need to be at wake up when we decide the CPU.
If we trigger the load balancing instead then it'd behave like a push/pull?
All these paths are already complex though. So we need to carefully analyze the trade-offs. Maybe we don't need to deliver such level of service after all. It needs more thinking and experimenting.
Thanks
-- Qais Yousef
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