On 19/06/20 12:57, Mel Gorman wrote: > On Fri, Jun 19, 2020 at 11:36:46AM +0100, Valentin Schneider wrote: >> > nouclamp uclamp >> > uclamp-static-key >> > Hmean send-64 162.43 ( 0.00%) 157.84 * -2.82%* >> > 163.39 * 0.59%* >> > Hmean send-128 324.71 ( 0.00%) 314.78 * -3.06%* >> > 326.18 * 0.45%* >> > Hmean send-256 641.55 ( 0.00%) 628.67 * -2.01%* >> > 648.12 * 1.02%* >> > Hmean send-1024 2525.28 ( 0.00%) 2448.26 * -3.05%* >> > 2543.73 * 0.73%* >> > Hmean send-2048 4836.14 ( 0.00%) 4712.08 * -2.57%* >> > 4867.69 * 0.65%* >> > Hmean send-3312 7540.83 ( 0.00%) 7425.45 * -1.53%* >> > 7621.06 * 1.06%* >> > Hmean send-4096 9124.53 ( 0.00%) 8948.82 * -1.93%* >> > 9276.25 * 1.66%* >> > Hmean send-8192 15589.67 ( 0.00%) 15486.35 * -0.66%* >> > 15819.98 * 1.48%* >> > Hmean send-16384 26386.47 ( 0.00%) 25752.25 * -2.40%* >> > 26773.74 * 1.47%* >> > >> >> Am I reading this correctly in that compiling in uclamp but having the >> static key enabled gives a slight improvement compared to not compiling in >> uclamp? I suppose the important bit is that we're not seeing regressions >> anymore, but still. >> > > I haven't reviewed the series in depth because from your review, another > version is likely in the works.
I don't wait Qais to hate me here - I think you could start the performance testing on this version if you feel like it, given my comments were mostly on changelog / debug options - the core of that patch shouldn't change much. > However, it is not that unusual to > see small fluctuations like this that are counter-intuitive. The report > indicates the difference is likely outside of the noise with * around the > percentage difference instead of () but it could be small boot-to-boot > variance, differences in code layout, slight differences in slab usage > patterns etc. The definitive evidence that uclamp overhead is no there > is whether the uclamp functions show up in annotated profiles or not. I see, thanks! I suppose if we have access to individual samples we can also run some statistical tests / stare at some boxplots to see how it compares.
