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Tue, 16 Sep 2025 22:19:55 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Wed, 17 Sep 2025 07:19:54 +0200 To: Suren Baghdasaryan Cc: Vlastimil Babka , paulmck@kernel.org, Jan Engelhardt , Sudarsan Mahendran , Liam.Howlett@oracle.com, cl@gentwo.org, harry.yoo@oracle.com, howlett@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, maple-tree@lists.infradead.org, rcu@vger.kernel.org, rientjes@google.com, roman.gushchin@linux.dev, urezki@gmail.com Subject: Re: Benchmarking [PATCH v5 00/14] SLUB percpu sheaves Message-ID: References: <20250723-slub-percpu-caches-v5-0-b792cd830f5d@suse.cz> <20250913000935.1021068-1-sudarsanm@google.com> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Sep 16, 2025 at 10:09:18AM -0700, Suren Baghdasaryan wrote: > On Mon, Sep 15, 2025 at 8:22 AM Vlastimil Babka 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? [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? Thank you. -- Uladzislau Rezki