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Tue, 22 Aug 2023 09:51:55 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 0zBzCDuF5GTGEgAAMHmgww (envelope-from ); Tue, 22 Aug 2023 09:51:55 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id A32F6A0774; Tue, 22 Aug 2023 11:51:54 +0200 (CEST) Date: Tue, 22 Aug 2023 11:51:54 +0200 From: Jan Kara To: Mateusz Guzik Cc: Dennis Zhou , linux-kernel@vger.kernel.org, tj@kernel.org, cl@linux.com, akpm@linux-foundation.org, shakeelb@google.com, linux-mm@kvack.org, jack@suse.cz Subject: Re: [PATCH 0/2] execve scalability issues, part 1 Message-ID: <20230822095154.7cr5ofogw552z3jk@quack3> References: <20230821202829.2163744-1-mjguzik@gmail.com> <20230821213951.bx3yyqh7omdvpyae@f> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 0F3C54000D X-Stat-Signature: enrb8yiyfizgq15q4u3tcqekwritostm X-HE-Tag: 1692697916-867785 X-HE-Meta: U2FsdGVkX18aFgh89/er2/aXu6J2g3Mk3ZQfSt7521PZZitwl95V0pt+63I9m9tvi7+/lpIQoEdRJ74XVU0IEdTzNj8A15xtbjDN9aQW0E1kpVLGd8gl7TdyOMei04PI+xlXAQ255u5xjgvtidJgQs0tEM6kKNY+kwHd6ERPuZzuBJX2OWvHIzlaPd1cgrV8nqrBY+pdY/InJd+ssVNxMhkWpnRqCl1clfQo8DfeV6VFVui6NLaAFSUEgWIQM/mcf3lKRgWvnRbzeuRQn/N1dzDQvIpuy8F3JQbk3JbKJzqMYR+UXD9ym3eyB4s11Kmg5M+99053AW3GEmZHiXfDlk+NGwU9PmDrmGhKcnuRjrNNHLx8ZchYyFKhxgwprwekvv5n01ejBYzR+R43NPqpSyVfTNNPUJ/nbXqHF/JQ2duF6wL9SpZoV+wi2qtjIVQ48fPzpiwAGhKPomocd23Akq4lg42Z3zMc3CpSHE2wh/RkHCPWGFGkXKgTZOLuiHA81TloLJua4ujUlTUpgkjsxhVHu0VWlNhmzdoGHTPTAR7i6+qY6QFOi4uYlFfYK3Fs3DkV/JYrS3CkNQaKB/OAibT8/kEv2O9Cq7LCnQREEvPWXQN0sqPjRCGxf4hhtuCfNEUllGIRfzSfcZau6SRv1QuI+wsBk6MyilVZldAxMvk5b4Y2NiXGmxl9/4reLP+/yts/UPo2cWKttZBooNeAHExHDPrCP2a0X65q6VWG2CAPl1wOrfcCYBPwDwboniLvg6DkaheOe4KEGVjR8jDOuO2xrIpPbP5bN8ZIXa+/68B9uVJP7SzJ0ApcYALk082kLzBZF3THwVzUyBqni6FgGI0RBeBUaNm78HaQ6ryl7gSWuaArttmCMH9BWrLIB/zV9tmmOq9bNN1irC4+gDC+QKtKd1WPrttgghUTR0zI8+yHXV5Z9KscIRxEtf0+sJKYSgadJY8ifzE6Zy7sKuc kTbv3lxs D4d+DhaZlluh+syQ631Bbp+O8oASTMvEuwxiqASIkPmtuEjIlKaNRTX9bLJOC4fpRluR2KxpSWTiurXHjhT87XQWVdErGU0UNsHh1ajJszSIuvmQKWunHebAN8e/Z6w38Nckkuab+jMhjL0vQ1ZDSCR5iivKqllrWpzLM7xiOo4GER8NQXdIFBkXa8KTmB7F352XnpmnZOf+/tHBTEhE2AieHYym2NzjqB3w3/dJzY6a93aG9aoTy9zz4De4qO7XHlQMmoXsDuJv/od15aNmSaef9ouqXo8CreHLad+sjoLqxIDluI3uTdKsiuVdYfoKbE7zq6tVqCJJZu1c= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 22-08-23 00:29:49, Mateusz Guzik wrote: > On 8/21/23, Mateusz Guzik wrote: > > True Fix(tm) is a longer story. > > > > Maybe let's sort out this patchset first, whichever way. :) > > > > So I found the discussion around the original patch with a perf > regression report. > > https://lore.kernel.org/linux-mm/20230608111408.s2minsenlcjow7q3@quack3/ > > The reporter suggests dodging the problem by only allocating per-cpu > counters when the process is going multithreaded. Given that there is > still plenty of forever single-threaded procs out there I think that's > does sound like a great plan regardless of what happens with this > patchset. > > Almost all access is already done using dedicated routines, so this > should be an afternoon churn to sort out, unless I missed a > showstopper. (maybe there is no good place to stuff a flag/whatever > other indicator about the state of counters?) > > That said I'll look into it some time this or next week. Good, just let me know how it went, I also wanted to start looking into this to come up with some concrete patches :). What I had in mind was that we could use 'counters == NULL' as an indication that the counter is still in 'single counter mode'. Honza -- Jan Kara SUSE Labs, CR