linux-kernel - Re: [PATCH 2/3] mm: page_counter: rearrange struct page

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Date:   Sun, 21 Aug 2022 21:55:28 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Soheil Hassas Yeganeh <soheil@...gle.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Muchun Song <songmuchun@...edance.com>,
        Michal Koutný <mkoutny@...e.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Feng Tang <feng.tang@...el.com>,
        Oliver Sang <oliver.sang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>, lkp@...ts.01.org,
        Cgroups <cgroups@...r.kernel.org>, linux-mm <linux-mm@...ck.org>,
        netdev <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] mm: page_counter: rearrange struct page_counter fields

On Sun, Aug 21, 2022 at 5:24 PM Soheil Hassas Yeganeh <soheil@...gle.com> wrote:
>
> On Sun, Aug 21, 2022 at 8:18 PM Shakeel Butt <shakeelb@...gle.com> wrote:
> >
> > With memcg v2 enabled, memcg->memory.usage is a very hot member for
> > the workloads doing memcg charging on multiple CPUs concurrently.
> > Particularly the network intensive workloads. In addition, there is a
> > false cache sharing between memory.usage and memory.high on the charge
> > path. This patch moves the usage into a separate cacheline and move all
> > the read most fields into separate cacheline.
> >
> > To evaluate the impact of this optimization, on a 72 CPUs machine, we
> > ran the following workload in a three level of cgroup hierarchy with top
> > level having min and low setup appropriately. More specifically
> > memory.min equal to size of netperf binary and memory.low double of
> > that.
> >
> >  $ 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              12413.7 Mbps (18.4% improvement)
> >
> > With the patch, the throughput improved by 18.4%.
>
> Shakeel, for my understanding: is this on top of the gains from the
> previous patch?
>

No, this is independent of the previous patch. The cover letter has
the numbers for all three optimizations applied together.