linux-kernel - Re: Benchmarking [PATCH v5 00/14] SLUB percpu sheaves

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: <CAJuCfpE48n=QM0nY8yE3drqZU0wgC76=70EyftL1WZewEcykyA@mail.gmail.com>
Date: Wed, 17 Sep 2025 16:59:41 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Uladzislau Rezki <urezki@...il.com>
Cc: Vlastimil Babka <vbabka@...e.cz>, paulmck@...nel.org, Jan Engelhardt <ej@...i.de>, 
	Sudarsan Mahendran <sudarsanm@...gle.com>, Liam.Howlett@...cle.com, cl@...two.org, 
	harry.yoo@...cle.com, howlett@...il.com, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, maple-tree@...ts.infradead.org, rcu@...r.kernel.org, 
	rientjes@...gle.com, roman.gushchin@...ux.dev
Subject: Re: Benchmarking [PATCH v5 00/14] SLUB percpu sheaves

On Wed, Sep 17, 2025 at 9:14 AM Suren Baghdasaryan <surenb@...gle.com> wrote:
>
> On Tue, Sep 16, 2025 at 10:19 PM Uladzislau Rezki <urezki@...il.com> wrote:
> >
> > On Tue, Sep 16, 2025 at 10:09:18AM -0700, Suren Baghdasaryan wrote:
> > > On Mon, Sep 15, 2025 at 8:22 AM Vlastimil Babka <vbabka@...e.cz> wrote:
> > > >
> > > > On 9/15/25 14:13, Paul E. McKenney wrote:
> > > > > On Mon, Sep 15, 2025 at 09:51:25AM +0200, Jan Engelhardt wrote:
> > > > >>
> > > > >> On Saturday 2025-09-13 02:09, Sudarsan Mahendran wrote:
> > > > >> >
> > > > >> >Summary of the results:
> > > >
> > > > In any case, thanks a lot for the results!
> > > >
> > > > >> >- Significant change (meaning >10% difference
> > > > >> >  between base and experiment) on will-it-scale
> > > > >> >  tests in AMD.
> > > > >> >
> > > > >> >Summary of AMD will-it-scale test changes:
> > > > >> >
> > > > >> >Number of runs : 15
> > > > >> >Direction      : + is good
> > > > >>
> > > > >> If STDDEV grows more than mean, there is more jitter,
> > > > >> which is not "good".
> > > > >
> > > > > This is true.  On the other hand, the mean grew way more in absolute
> > > > > terms than did STDDEV.  So might this be a reasonable tradeoff?
> > > >
> > > > Also I'd point out that MIN of TEST is better than MAX of BASE, which means
> > > > there's always an improvement for this config. So jitter here means it's
> > > > changing between better and more better :) and not between worse and (more)
> > > > better.
> > > >
> > > > The annoying part of course is that for other configs it's consistently the
> > > > opposite.
> > >
> > > Hi Vlastimil,
> > > I ran my mmap stress test that runs 20000 cycles of mmapping 50 VMAs,
> > > faulting them in then unmapping and timing only mmap and munmap calls.
> > > This is not a realistic scenario but works well for A/B comparison.
> > >
> > > The numbers are below with sheaves showing a clear improvement:
> > >
> > > Baseline
> > >             avg             stdev
> > > mmap        2.621073        0.2525161631
> > > munmap      2.292965        0.008831973052
> > > total       4.914038        0.2572620923
> > >
> > > Sheaves
> > >             avg            stdev           avg_diff        stdev_diff
> > > mmap        1.561220667    0.07748897037   -40.44%        -69.31%
> > > munmap      2.042071       0.03603083448   -10.94%        307.96%
> > > total       3.603291667    0.113209047     -26.67%        -55.99%
> > >
> > Could you run your test with dropping below patch?
>
> Sure, will try later today and report.

Sheaves with [04/23] patch reverted:

            avg             avg_diff
mmap     2.143948        -18.20%
munmap     2.343707        2.21%
total     4.487655        -8.68%


>
> >
> > [PATCH v8 04/23] slab: add sheaf support for batching kfree_rcu() operations
> >
> > mmap()/munmap(), i assume it is a duration time in average, is the time
> > in microseconds?
>
> Yeah, it ends up being in microseconds. The actual reported time is
> the total time in seconds that all mmap/munmap in the test consumed.
> With 20000 cycles of 50 mmap/munmap calls we end up with 1000000
> syscalls, so the number can be considered as duration in microseconds
> for a single call.
>
> >
> > Thank you.
> >
> > --
> > Uladzislau Rezki