From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 354BAC433B4 for ; Tue, 20 Apr 2021 09:49:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DDA8E613B2 for ; Tue, 20 Apr 2021 09:49:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231453AbhDTJte (ORCPT ); Tue, 20 Apr 2021 05:49:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45744 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231246AbhDTJtd (ORCPT ); Tue, 20 Apr 2021 05:49:33 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9695C06174A for ; Tue, 20 Apr 2021 02:49:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=c/4ebdPoDkXsRQNBUYWS70TUfZuUFjko8Cp0we1f+BM=; b=BulSmpljSK+FX7V38AZr3XoNb6 CylJg8sIm/YyS9UMI9z82G6/ycIVoB1vQmu5dk/kLGkmceZn4UpjRT4zo4gdKSX7M6WwQW9MmG8Ft ZQTHBEI7RT5iiEFnu3nJHmGBSppCeMcXBjWd7Ls3VLLAR0dy/ElHWx8nrM0D+kJKXY6IwID4zHaho rEEOxgoEOyBlY/w5FwZCtypV53bhyWVj+teXoScwmnrdlbh1RwRbZTmMJBk9CvUIZOXdyJ7isAEsh W8EQZX3vlPg/nHJIJ6wrviZvJHVOpMOt6U2PZBIyDhLUHxxnV4WoFcioPLYE0w7yBYcwMKRrhafmv /NV1+A5g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lYmzx-00BoJe-4j; Tue, 20 Apr 2021 09:48:49 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 58725300130; Tue, 20 Apr 2021 11:48:48 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3E6EE2C48E3A3; Tue, 20 Apr 2021 11:48:48 +0200 (CEST) Date: Tue, 20 Apr 2021 11:48:48 +0200 From: Peter Zijlstra To: Stephane Eranian Cc: Namhyung Kim , Ingo Molnar , Arnaldo Carvalho de Melo , Jiri Olsa , Mark Rutland , Alexander Shishkin , LKML , Andi Kleen , Ian Rogers , Song Liu , Tejun Heo , kernel test robot , Thomas Gleixner Subject: Re: [PATCH v3 1/2] perf/core: Share an event with multiple cgroups Message-ID: References: <20210413155337.644993-1-namhyung@kernel.org> <20210413155337.644993-2-namhyung@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 20, 2021 at 01:34:40AM -0700, Stephane Eranian wrote: > The sampling approach will certainly incur more overhead and be at > risk of losing the ability to > reconstruct the total counter per-cgroup, unless you set the period > for SW_CGROUP_SWITCHES to > 1. But then, you run the risk of losing samples if the buffer is full > or sampling is throtlled. > In some scenarios, we believe the number of context switches between > cgroup could be quite high (>> 1000/s). > And on top you would have to add the processing of the samples to > extract the counts per cgroup. That would require > a synthesis on cgroup on perf record and some post-processing on perf > report. We are interested in using the data live > to make some policy decisions, so a counting approach with perf stat > will always be best. Can you please configure your MUA to sanely (re)flow text? The above random line-breaks are *so* painful to read.