Messages in this thread | | | From | Joel Fernandes <> | Date | Thu, 14 Dec 2017 09:08:27 -0800 | Subject | Re: [PATCH] sched/fair: Consider RT/IRQ pressure in capacity_spare_wake |
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Hi Vincent, Thanks for your reply.
On Thu, Dec 14, 2017 at 7:46 AM, Vincent Guittot <vincent.guittot@linaro.org> wrote: > Hi Joel, > > On 13 December 2017 at 21:00, Joel Fernandes <joelaf@google.com> wrote: >> On Mon, Dec 11, 2017 at 4:43 PM, Joel Fernandes <joelaf@google.com> wrote: >>> Hi Vincent, >>> >>>>> >>>>>> >>>>>>> ------------------------------------------------------------ >>>>>>> Here we have RT activity running on big CPU cluster induced with rt-app, >>>>>>> and running hackbench in parallel. The RT tasks are bound to 4 CPUs on >>>>>>> the big cluster (cpu 4,5,6,7) and have 100ms periodicity with >>>>>>> runtime=20ms sleep=80ms. >>>>>>> >>>>>>> Hackbench shows big benefit (30%) improvement when number of tasks is 8 >>>>>>> and 32: Note: data is completion time in seconds (lower is better). >>>>>>> Number of loops for 8 and 16 tasks is 50000, and for 32 tasks its 20000. >>>>>>> +--------+-----+-------+-------------------+---------------------------+ >>>>>>> | groups | fds | tasks | Without Patch | With Patch | >>>>>>> +--------+-----+-------+---------+---------+-----------------+---------+ >>>>>>> | | | | Mean | Stdev | Mean | Stdev | >>>>>>> | | | +-------------------+-----------------+---------+ >>>>>>> | 1 | 8 | 8 | 1.0534 | 0.13722 | 0.7293 (+30.7%) | 0.02653 | >>>>>>> | 2 | 8 | 16 | 1.6219 | 0.16631 | 1.6391 (-1%) | 0.24001 | >>>>>>> | 4 | 8 | 32 | 1.2538 | 0.13086 | 1.1080 (+11.6%) | 0.16201 | >>>>>>> +--------+-----+-------+---------+---------+-----------------+---------+ >>>>>> >>>>>> Out of curiosity, do you know why you don't see any improvement for >>>>>> 16 tasks but only for 8 and 32 tasks ? >>>>> >>>>> Yes I'm not fully sure why 16 tasks didn't show that much improvement. >>>> >>>> Yes. This is just to make sure that there no unexpected side effect >>> >> >> It could have been sloppy testing - I could have hit thermal >> throttling or forgotten to stop Android runtime before running the >> test. Looking at my old data, the case for 16 tasks has higher >> completion times than 32 tasks which doesn't make sense. Sorry about >> that. I was careful this time, I recreated the product tree and >> applied patch - ran the same test as in this patch, the data prefixed >> with "with" is with patch and "without" is without patch. >> >> The naming of the Test column is "<test>-<numFDs>-<numGroups>". Data >> is completion time of hackbench in seconds. >> >> RUN 1: >> >> Test Mean Median Stddev >> with-f4-1g 0.67645 (+3.7%) 0.68000 (+3.8%) 0.025755 >> with-f4-2g 1.0685 (-0.3%) 1.0570 (+1%) 0.044122 >> with-f4-4g 1.7558 (+0.7%) 1.7685 (+0.08%) 0.096015 >> >> without-f4-1g 0.70255 0.70750 0.025330 >> without-f4-2g 1.0653 1.0680 0.040300 >> without-f4-4g 1.7688 1.7670 0.046341 >> >> RUN 2: >> >> Test Mean Median Stddev >> with-f4-1g 0.68100 (+1%) 0.67800 (+2%) 0.025543 >> with-f4-2g 1.0242 (+1.5%) 1.0260 (+1.5%) 0.042886 >> with-f4-4g 1.6100 (+3%) 1.6075 (+3.7%) 0.052677 >> >> without-f4-1g 0.68840 0.69150 0.030988 >> without-f4-2g 1.0400 1.0420 0.034288 >> without-f4-4g 1.6636 1.6670 0.056963 >> >> >> Let me know what you think, thanks. > > The improvement has decreased compared to previous results and there
Yes but the previous result was invalid as I mentioned, I controlled the environment better this time. Previous result showed 4g completed quicker than 2g which wasn't very meaningful.
> is instability between your runs; As an example, run2 without patch > does better than run1 with patchs for 2g and 4g.
That's true. The improvement percent isn't stable.
> Could you run tests on a SMP linux kernel instead of big/LITTLE > android in order to have a saner test environnement and remove some > possible disturbances
Would it be Ok with you if I just dropped this synthetic test from the patch since there are other hackbench results (case 3) from Rohit which are on SMP?
Thanks,
- Joel
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