On Tuesday 29 May 2018 at 17:02:29 (+0200), Vincent Guittot wrote: > Hi Quentin, > > On 29 May 2018 at 16:55, Quentin Perret <quentin.per...@arm.com> wrote: > > > > On Friday 25 May 2018 at 19:04:55 (+0100), Patrick Bellasi wrote: > > > On 25-May 15:26, Quentin Perret wrote: > > > > And also, I understand these functions are large, but if we _really_ > > > > want to inline them even though they're big, why not putting them in > > > > sched-pelt.h ? > > > > > > Had the same tought at first... but then I recalled that header is > > > generated from a script. Thus, eventually, it should be a different one. > > > > Ah, good point. This patch already introduces a pelt.h so I guess that > > could work as well. > > > > > > > > > We probably wouldn't accept that for everything, but > > > > those PELT functions are used all over the place, including latency > > > > sensitive code paths (e.g. task wake-up). > > > > > > We should better measure the overheads, if any, and check what > > > (a modern) compiler does. Maybe some hackbench run could help on the > > > first point. > > > > FWIW, I ran a few hackbench tests today on my Intel box: > > - Intel i7-6700 (4 cores / 8 threads) @ 3.40GHz > > - Base kernel: today's tip/sched/core "2539fc82aa9b sched/fair: Update > > util_est before updating schedutil" > > - Compiler: GCC 7.3.0 > > Which cpufreq governor are you using ?
powersave, with the intel_pstate driver. > > > > > The tables below summarize the results for: > > perf stat --repeat 10 perf bench sched messaging --pipe --thread -l 50000 > > --group G > > > > Without patch: > > +---+-------+----------+---------+ > > | G | Tasks | Duration | Stddev | > > +---+-------+----------+---------+ > > | 1 | 40 | 3.906 | +-0.84% | > > | 2 | 80 | 8.569 | +-0.77% | > > | 4 | 160 | 16.384 | +-0.46% | > > | 8 | 320 | 33.686 | +-0.42% | > > +---+-------+----------+---------+ > > > > With patch: > > Just to make sure. You mean only this patch and not the whole patchset ? That's right, I applied only this patch. > > > +---+-------+----------------+---------+ > > | G | Tasks | Duration | Stddev | > > +---+-------+----------------+---------+ > > | 1 | 40 | 3.953 (+1.2%) | +-1.43% | > > | 2 | 80 | 8.646 (+0.9%) | +-0.32% | > > | 4 | 160 | 16.390 (+0.0%) | +-0.38% | > > | 8 | 320 | 33.992 (+0.9%) | +-0.27% | > > +---+-------+----------------+---------+ > > > > So there is (maybe) a little something on my box, but not so significant > > IMHO ... :) > > > > Thanks, > > Quentin
