Re: [PATCH v2 3/3] memcg: increase MEMCG_CHARGE_BATCH to 64

[Muchun Song <muchun.song-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>]

> On Aug 25, 2022, at 08:05, Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> wrote:
> 
> For several years, MEMCG_CHARGE_BATCH was kept at 32 but with bigger
> machines and the network intensive workloads requiring througput in
> Gbps, 32 is too small and makes the memcg charging path a bottleneck.
> For now, increase it to 64 for easy acceptance to 6.0. We will need to
> revisit this in future for ever increasing demand of higher performance.
> 
> Please note that the memcg charge path drain the per-cpu memcg charge
> stock, so there should not be any oom behavior change. Though it does
> have impact on rstat flushing and high limit reclaim backoff.
> 
> To evaluate the impact of this optimization, on a 72 CPUs machine, we
> ran the following workload in a three level of cgroup hierarchy.
> 
> $ netserver -6
> # 36 instances of netperf with following params
> $ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K
> 
> Results (average throughput of netperf):
> Without (6.0-rc1)       10482.7 Mbps
> With patch              17064.7 Mbps (62.7% improvement)
> 
> With the patch, the throughput improved by 62.7%.

This is very impressive.

> 
> Signed-off-by: Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Reported-by: kernel test robot <oliver.sang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Acked-by: Soheil Hassas Yeganeh <soheil-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Reviewed-by: Feng Tang <feng.tang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Acked-by: Roman Gushchin <roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>

Acked-by: Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>

Thanks.