On 06/19/20 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. 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.
The diff between nouclamp and uclamp-static-key (disabling uclamp in fast path)
8.73% -1.55% [kernel.kallsyms] [k] try_to_wake_up
0.07% +0.04% [kernel.kallsyms] [k] deactivate_task
0.13% -0.02% [kernel.kallsyms] [k] activate_task
The diff between nouclamp and uclamp-static-key (uclamp actively used in the
fast path)
8.73% -0.72% [kernel.kallsyms] [k] try_to_wake_up
0.13% +0.39% [kernel.kallsyms] [k] activate_task
0.07% +0.38% [kernel.kallsyms] [k] deactivate_task
I will include these numbers in the commit message in v2.
Thanks
--
Qais Yousef
