On Fri, Mar 15, 2019 at 11:30:42AM -0400, Phil Auld wrote: > In my defense here, all the fair.c imbalance pct code also uses 100 :)
Yes, I know, I hate on that too ;-) Just never got around to fixing that. > with the below: > > [ 117.235804] cfs_period_timer[cpu2]: period too short, scaling up (new > cfs_period_us 2492, cfs_quota_us = 143554) > [ 117.346807] cfs_period_timer[cpu2]: period too short, scaling up (new > cfs_period_us 2862, cfs_quota_us = 164863) > [ 117.470569] cfs_period_timer[cpu2]: period too short, scaling up (new > cfs_period_us 3286, cfs_quota_us = 189335) > [ 117.574883] cfs_period_timer[cpu2]: period too short, scaling up (new > cfs_period_us 3774, cfs_quota_us = 217439) > [ 117.652907] cfs_period_timer[cpu2]: period too short, scaling up (new > cfs_period_us 4335, cfs_quota_us = 249716) > [ 118.090535] cfs_period_timer[cpu2]: period too short, scaling up (new > cfs_period_us 4978, cfs_quota_us = 286783) > [ 122.098009] cfs_period_timer[cpu2]: period too short, scaling up (new > cfs_period_us 5717, cfs_quota_us = 329352) > [ 126.255209] cfs_period_timer[cpu2]: period too short, scaling up (new > cfs_period_us 6566, cfs_quota_us = 378240) > [ 126.358060] cfs_period_timer[cpu2]: period too short, scaling up (new > cfs_period_us 7540, cfs_quota_us = 434385) > [ 126.538358] cfs_period_timer[cpu9]: period too short, scaling up (new > cfs_period_us 8660, cfs_quota_us = 498865) > [ 126.614304] cfs_period_timer[cpu9]: period too short, scaling up (new > cfs_period_us 9945, cfs_quota_us = 572915) > [ 126.817085] cfs_period_timer[cpu9]: period too short, scaling up (new > cfs_period_us 11422, cfs_quota_us = 657957) > [ 127.352038] cfs_period_timer[cpu9]: period too short, scaling up (new > cfs_period_us 13117, cfs_quota_us = 755623) > [ 127.598043] cfs_period_timer[cpu9]: period too short, scaling up (new > cfs_period_us 15064, cfs_quota_us = 867785) > > > Plus on repeats I see an occasional > > [ 152.803384] sched_cfs_period_timer: 9 callbacks suppressed That should be fine, right? It's a fallback for an edge case and shouldn't trigger too often anyway. >> I'll rework the maths in the averaged version and post v2 if that makes >> sense. > > It may have the extra timer fetch, although maybe I could rework it so that > it used the > nsstart time the first time and did not need to do it twice in a row. I had > originally > reverted the hrtimer_forward_now() to hrtimer_forward() but put that back. Sure; but remember, simpler is often better, esp. for code that typically 'never' runs. > Also, fwiw, this was reported earlier by Anton Blanchard in > https://lkml.org/lkml/2018/12/3/1047 Bah, yes, I sometimes loose track of things :/
