On Mon, Aug 05, 2019 at 04:09:15PM -0400, Phil Auld wrote: > Hi, > > On Fri, Aug 02, 2019 at 11:37:15AM -0400 Julien Desfossez wrote: > > We tested both Aaron's and Tim's patches and here are our results. > > > > Test setup: > > - 2 1-thread sysbench, one running the cpu benchmark, the other one the > > mem benchmark > > - both started at the same time > > - both are pinned on the same core (2 hardware threads) > > - 10 30-seconds runs > > - test script: https://paste.debian.net/plainh/834cf45c > > - only showing the CPU events/sec (higher is better) > > - tested 4 tag configurations: > > - no tag > > - sysbench mem untagged, sysbench cpu tagged > > - sysbench mem tagged, sysbench cpu untagged > > - both tagged with a different tag > > - "Alone" is the sysbench CPU running alone on the core, no tag > > - "nosmt" is both sysbench pinned on the same hardware thread, no tag > > - "Tim's full patchset + sched" is an experiment with Tim's patchset > > combined with Aaron's "hack patch" to get rid of the remaining deep > > idle cases > > - In all test cases, both tasks can run simultaneously (which was not > > the case without those patches), but the standard deviation is a > > pretty good indicator of the fairness/consistency. > > > > No tag > > ------ > > Test Average Stdev > > Alone 1306.90 0.94 > > nosmt 649.95 1.44 > > Aaron's full patchset: 828.15 32.45 > > Aaron's first 2 patches: 832.12 36.53 > > Aaron's 3rd patch alone: 864.21 3.68 > > Tim's full patchset: 852.50 4.11 > > Tim's full patchset + sched: 852.59 8.25 > > > > Sysbench mem untagged, sysbench cpu tagged > > ------------------------------------------ > > Test Average Stdev > > Alone 1306.90 0.94 > > nosmt 649.95 1.44 > > Aaron's full patchset: 586.06 1.77 > > Aaron's first 2 patches: 630.08 47.30 > > Aaron's 3rd patch alone: 1086.65 246.54 > > Tim's full patchset: 852.50 4.11 > > Tim's full patchset + sched: 390.49 15.76 > > > > Sysbench mem tagged, sysbench cpu untagged > > ------------------------------------------ > > Test Average Stdev > > Alone 1306.90 0.94 > > nosmt 649.95 1.44 > > Aaron's full patchset: 583.77 3.52 > > Aaron's first 2 patches: 513.63 63.09 > > Aaron's 3rd patch alone: 1171.23 3.35 > > Tim's full patchset: 564.04 58.05 > > Tim's full patchset + sched: 1026.16 49.43 > > > > Both sysbench tagged > > -------------------- > > Test Average Stdev > > Alone 1306.90 0.94 > > nosmt 649.95 1.44 > > Aaron's full patchset: 582.15 3.75 > > Aaron's first 2 patches: 561.07 91.61 > > Aaron's 3rd patch alone: 638.49 231.06 > > Tim's full patchset: 679.43 70.07 > > Tim's full patchset + sched: 664.34 210.14 > > > > Sorry if I'm missing something obvious here but with only 2 processes > of interest shouldn't one tagged and one untagged be about the same > as both tagged?
It should. > In both cases the 2 sysbenches should not be running on the core at > the same time. Agree. > There will be times when oher non-related threads could share the core > with the untagged one. Is that enough to account for this difference? What difference do you mean? Thanks, Aaron > > So in terms of fairness, Aaron's full patchset is the most consistent, but > > only > > Tim's patchset performs better than nosmt in some conditions. > > > > Of course, this is one of the worst case scenario, as soon as we have > > multithreaded applications on overcommitted systems, core scheduling > > performs > > better than nosmt. > > > > Thanks, > > > > Julien > > --
