On Wed, Sep 17, 2025 at 9:14 AM Suren Baghdasaryan <[email protected]> wrote:
>
> On Tue, Sep 16, 2025 at 10:19 PM Uladzislau Rezki <[email protected]> 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 <[email protected]> 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
