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SubjectRe: [RFC PATCH v2 00/17] Core scheduling v2
On 24-Apr-2019 09:13:10 PM, Aubrey Li wrote:
> On Wed, Apr 24, 2019 at 12:18 AM Vineeth Remanan Pillai
> <vpillai@digitalocean.com> wrote:
> >
> > Second iteration of the core-scheduling feature.
> >
> > This version fixes apparent bugs and performance issues in v1. This
> > doesn't fully address the issue of core sharing between processes
> > with different tags. Core sharing still happens 1% to 5% of the time
> > based on the nature of workload and timing of the runnable processes.
> >
> > Changes in v2
> > -------------
> > - rebased on mainline commit: 6d906f99817951e2257d577656899da02bb33105
>
> Thanks to post v2, based on this version, here is my benchmarks result.
>
> Environment setup
> --------------------------
> Skylake server, 2 numa nodes, 104 CPUs (HT on)
> cgroup1 workload, sysbench (CPU intensive non AVX workload)
> cgroup2 workload, gemmbench (AVX512 workload)
>
> Case 1: task number < CPU num
> --------------------------------------------
> 36 sysbench threads in cgroup1
> 36 gemmbench threads in cgroup2
>
> core sched off:
> - sysbench 95th percentile latency(ms): avg = 4.952, stddev = 0.55342
> core sched on:
> - sysbench 95th percentile latency(ms): avg = 3.549, stddev = 0.04449
>
> Due to core cookie matching, sysbench tasks won't be affect by AVX512
> tasks, latency has ~28% improvement!!!
>
> Case 2: task number > CPU number
> -------------------------------------------------
> 72 sysbench threads in cgroup1
> 72 gemmbench threads in cgroup2
>
> core sched off:
> - sysbench 95th percentile latency(ms): avg = 11.914, stddev = 3.259
> core sched on:
> - sysbench 95th percentile latency(ms): avg = 13.289, stddev = 4.863
>
> So not only power, now security and performance is a pair of contradictions.
> Due to core cookie not matching and forced idle introduced, latency has ~12%
> regression.
>
> Any comments?

Would it be possible to post the results with HT off as well ?

Thanks,

Julien

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