Messages in this thread | | | From | Vincent Guittot <> | Date | Fri, 21 Feb 2020 14:28:50 +0100 | Subject | Re: [PATCH v3 4/5] sched/pelt: Add a new runnable average signal |
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On Fri, 21 Feb 2020 at 11:40, Mel Gorman <mgorman@suse.de> wrote: > > On Fri, Feb 21, 2020 at 10:25:27AM +0100, Vincent Guittot wrote: > > On Fri, 21 Feb 2020 at 10:04, Mel Gorman <mgorman@suse.de> wrote: > > > > > > 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. > > > > I'm going to send a new version at least for patch 4 and 5 using > > cpu_scale as initial value and fixing update_sg_wakeup_stats() > > > > No problem. FWIW, when I see them, I'll slot them in and rerun the tests > as the previous results will be invalidated. Obviously the asym case will
I have just sent the new version. Thanks for testing
> not be tested by me but I imagine you or Valentin have that covered. > > Thanks. > > -- > Mel Gorman > SUSE Labs
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