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. > > [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
