On 14 December 2017 at 18:08, Joel Fernandes <[email protected]> wrote: > Hi Vincent, > Thanks for your reply. > > On Thu, Dec 14, 2017 at 7:46 AM, Vincent Guittot > <[email protected]> wrote: >> Hi Joel, >> >> On 13 December 2017 at 21:00, Joel Fernandes <[email protected]> wrote: >>> On Mon, Dec 11, 2017 at 4:43 PM, Joel Fernandes <[email protected]> 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.
Yes. It was just to highlight that we don't see improvements for this test anymore with new results > >> 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? Yes you can probably remove it as there is no improvement and others tests show improvement > > Thanks, > > - Joel
