linux-kernel - Re: [linus:master] [mm] f1a7941243: unixbench.score -19.2% regression

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CALvZod7wP9n+cqJV4VN3YNnf6CPQ8PJZbkAgK=fv84D4Sk+Heg@mail.gmail.com>
Date:   Mon, 27 Feb 2023 08:50:07 -0800
From:   Shakeel Butt <shakeelb@...gle.com>
To:     "Yin, Fengwei" <fengwei.yin@...el.com>
Cc:     "willy@...radead.org" <willy@...radead.org>,
        "tj@...nel.org" <tj@...nel.org>,
        "dennis@...nel.org" <dennis@...nel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        lkp <lkp@...el.com>,
        "zhengjun.xing@...ux.intel.com" <zhengjun.xing@...ux.intel.com>,
        "Huang, Ying" <ying.huang@...el.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "Tang, Feng" <feng.tang@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
        "Sang, Oliver" <oliver.sang@...el.com>,
        "linux-trace-kernel@...r.kernel.org" 
        <linux-trace-kernel@...r.kernel.org>,
        "oe-lkp@...ts.linux.dev" <oe-lkp@...ts.linux.dev>
Subject: Re: [linus:master] [mm] f1a7941243: unixbench.score -19.2% regression

On Sun, Feb 26, 2023 at 10:35 PM Yin, Fengwei <fengwei.yin@...el.com> wrote:
>
> Hi Andrew, Shakeel,
>
> On Tue, 2023-01-31 at 10:26 -0800, Shakeel Butt wrote:
> > +per-cpu memory maintainers for FYI.
> >
> > Thread started at
> > https://lore.kernel.org/linux-mm/202301301057.e55dad5b-oliver.sang@intel.com/
> >
> > On Mon, Jan 30, 2023 at 9:57 PM Shakeel Butt <shakeelb@...gle.com>
> > wrote:
> > >
> > [...]
> > > >
> > > > We could cut down the number of calls to pcpu_alloc() by a factor
> > > > of 4
> > > > by having a pcpu_alloc_bulk() that would allocate all four RSS
> > > > counters
> > > > at once.
> > > >
> > > > Just throwing out ideas ...
> > >
> > > Thanks, I will take a stab at pcpu_alloc_bulk() and will share the
> > > result tomorrow.
> > >
> >
> > OK, not a one day effort.
> >
> > Andrew, which option do you prefer?
> >
> > 1. Keep the patches as the test workload (fork ping pong) is not a
> > representative of real world workload and work on improving
> > pcpu_alloc() for 6.4+.
> >
> > 2. Revert the patches for now, improve pcpu_alloc() and re-introduce
> > the patches once we confirm that fork-ping-pong is not regressed
> > anymore.
> This performance regression still can be reproduced on latest master
> branch. So we took option1 here. Right? Thanks.
>

Yes unless some real workload reports regression.

Shakeel