Messages in this thread | | | From | Vincent Guittot <> | Date | Sun, 10 Nov 2019 16:13:14 +0100 | Subject | Re: [PATCH] Revert "sched/fair: Fix O(nr_cgroups) in the load balancing path" |
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Hi Doug,
On Sat, 9 Nov 2019 at 17:47, Doug Smythies <dsmythies@telus.net> wrote: > > Hi Vincent, > > Thank you for your item 2 patch. > > On 2019.11.08 01:19 Vincent Guittot wrote: > ... > >> I have to prepare a patch for this part which is item 2 > > > > I have finally been able to prepared the patch for item 2. Could you check > > that it also fixes your problem ? > ... > > We can still have some spurious call to cpufreq_util_change in > > update_blocked_average() with this patch but at least the value will be > > up to date in both calls, which was not the case before. If this fix > > Doug's problem, I can prepare an additional one to fix the spurious call > > but I wanted to make sure that this fix the problem first. > > Yes, the issue is solved with this patch.
Thanks for your tests
> I do wonder if I am seeing the effect of the spurious calls.
I don't think so because the spurious calls are in fact a 2nd call during the same update_blocked_average and from what i have seen , intel pstate driver filter call when there is less than 3 or 10ms between the 2 calls
> > Details: > > Test 1: an 8000 second trace during system idle: > Maximum duration: 4.00015 seconds. Good. > Typically, there would have been about 300 durations > of over 10 seconds in 8000 seconds. > Number of calls to driver: 103168, which is about 8% more than > the previous experimental solution. > (Should be repeated a few times to verify repeatability, but > not going to.) > > Test 2: one 8000 second energy sample, for high accuracy idle power: > 3.703 watts which is about +0.7% idle power increase. > > Test 3: The load-no-load test with only idle state 1 enabled: > There was never an excessive energy sample for the no load samples. > The test ran for about 8 hours. > Maximum: 9.49 watts > Minimum: 9.13 watts > Recall that with the issue, the max would have been about 14 watts > > Kernel: 5.4-rc6 + your items 1 and item 2 patches. > Idle governor = menu, because teo fixes are still pending. > Note: some reference data is from kernel 5.4-rc2, and really > should have been re-done with 5.4-rc6 as the baseline. > > ... Doug > >
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