Received: by 2002:ac0:a581:0:0:0:0:0 with SMTP id m1-v6csp471618imm; Tue, 3 Jul 2018 23:57:59 -0700 (PDT) X-Google-Smtp-Source: AAOMgpe21qZTFXRKO3f8lJkvBzHqKI4q2GQe0+FYe3IAHkwBmQRE0Dy00Z8r80/5oKf3evvlOG/e X-Received: by 2002:a63:27c1:: with SMTP id n184-v6mr757695pgn.29.1530687479181; Tue, 03 Jul 2018 23:57:59 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1530687479; cv=none; d=google.com; s=arc-20160816; b=Dsy/MJ9PzGWZ6b3hv2oxmZSxZJIlHsNYFNWf/kmLzS18y6VIUMXAuUV/TDufYAkHV4 aYqzf+mDsE5jdYa6dWI99OkuecsH1X4n3ZDQnESdBBv6D2Y28+kClruCjbjzzJNl84EW FAbkt30Psv1vJ/3exyELHXQA0X4uHSYmxcmQEmAx2PFdf4SMsq9yPQH4BpPr1PoLD8uU FhI3AzjrrLHYgF35IRJjUt1o/UDt0fd8Nev7labcaUwpEbYXTh0y03A2QBu4ygSPFB1r eZzqc2vSDvaLO53nGuPuMrjRXpC/rcvQYeAt3yS3cDAKrkMK67VxIF9pDiQWB5DUtkpT t0RQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:in-reply-to :mime-version:user-agent:date:message-id:from:references:cc:to :subject:reply-to:arc-authentication-results; bh=lpLlArl686+IisrULa2G9Go5bfQ9dXNef8ENO9j/YEA=; b=v8LmvZksuMDojEigWiQ3RG2725ZUn9F8u0e5ZdTl2GsZiAio+y2aHbEa2hepFTF67W zIoh0bH/lAcI7+uBiZiFnEo2Q8CnW92CGSluqshD/gGlPgmrTGsJJtrGy2KPYnRl8FL+ udjMo1WLGdKY2aXRl17KivW6zzxan0uXfY3BZkqjxvMVQtuDjW4kvlGpFr5OUds4AXHe kSKhvDqLWWSX2jEz9rktuaaFJqpR9CwhYuF4/wUxQeG9hJcDpeAzXjfdJOjd3nnH+SM/ CN+suGy8y/3A16fij97EiNr1A5Q8WQTQVoKjnk/38b6NRyzgud16SfBLbPNmeygGW9yU k4zg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=alibaba.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id d2-v6si2814120plh.387.2018.07.03.23.57.44; Tue, 03 Jul 2018 23:57:59 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=alibaba.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933440AbeGDG5A (ORCPT + 99 others); Wed, 4 Jul 2018 02:57:00 -0400 Received: from out30-133.freemail.mail.aliyun.com ([115.124.30.133]:45485 "EHLO out30-133.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932420AbeGDG47 (ORCPT ); Wed, 4 Jul 2018 02:56:59 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R951e4;CH=green;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04455;MF=xlpang@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0T3x1A3P_1530687402; Received: from xunleideMacBook-Pro.local(mailfrom:xlpang@linux.alibaba.com fp:SMTPD_---0T3x1A3P_1530687402) by smtp.aliyun-inc.com(127.0.0.1); Wed, 04 Jul 2018 14:56:42 +0800 Reply-To: xlpang@linux.alibaba.com Subject: Re: [PATCH] sched/cputime: Ensure correct utime and stime proportion To: Tejun Heo , Peter Zijlstra Cc: Ingo Molnar , Frederic Weisbecker , linux-kernel@vger.kernel.org References: <20180622071542.61569-1-xlpang@linux.alibaba.com> <20180626154908.GE2458@hirez.programming.kicks-ass.net> <20180702152106.GD533219@devbig577.frc2.facebook.com> From: Xunlei Pang Message-ID: <351ef694-92b5-bd43-e766-19e1a1e71453@linux.alibaba.com> Date: Wed, 4 Jul 2018 14:56:42 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180702152106.GD533219@devbig577.frc2.facebook.com> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/2/18 11:21 PM, Tejun Heo wrote: > Hello, Peter. > > On Tue, Jun 26, 2018 at 05:49:08PM +0200, Peter Zijlstra wrote: >> Well, no, because the Changelog is incomprehensible and the patch >> doesn't really have useful comments, so I'll have to reverse engineer >> the entire thing, and I've just not had time for that. > > Just as an additional data point, we also sometimes see artifacts from > cpu_adjust_time() in the form of per-task user or sys time getting > stuck for some period (in extreme cases for over a minute) while the > application isn't doing anything differently. We're telling the users > that it's an inherent sampling artifact but it'd be nice to improve it > if possible without adding noticeable overhead. No idea whether this > patch's approach is a good one tho. The patch has no noticeable overhead except the extra cputime fileds added into task_struct. We've been running this patch on our servers for months, looks good till now. Thanks!