Messages in this thread | | | Date | Fri, 21 Feb 2020 09:04:48 +0000 | From | Mel Gorman <> | Subject | Re: [PATCH v3 4/5] sched/pelt: Add a new runnable average signal |
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On Thu, Feb 20, 2020 at 04:11:18PM +0000, Valentin Schneider wrote: > On 20/02/2020 14:36, Vincent Guittot wrote: > > I agree that setting by default to SCHED_CAPACITY_SCALE is too much > > for little core. > > The problem for little core can be fixed by using the cpu capacity instead > > > > So that's indeed better for big.LITTLE & co. Any reason however for not > aligning with the initialization of util_avg ? > > With the default MC imbalance_pct (117), it takes 875 utilization to make > a single CPU group (with 1024 capacity) overloaded (group_is_overloaded()). > For a completely idle CPU, that means forking at least 3 tasks (512 + 256 + > 128 util_avg) > > With your change, it only takes 2 tasks. I know I'm being nitpicky here, but > I feel like those should be aligned, unless we have a proper argument against > it - in which case this should also appear in the changelog with so far only > mentions issues with util_avg migration, not the fork time initialization. >
So, what is the way forward here? Should this patch be modified now, a patch be placed on top or go with what we have for the moment that works for symmetric CPUs and deal with the asym case later?
I do not have any asym systems at all so I've no means of checking whether there is a problem or not.
-- Mel Gorman SUSE Labs
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