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 is instability between your runs; As an example, run2 without patch does better than run1 with patchs for 2g and 4g. 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 Vincent > > - Joel
