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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham 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 CE518C3279B for ; Wed, 4 Jul 2018 06:57:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CE0C2473A for ; Wed, 4 Jul 2018 06:57:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7CE0C2473A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933464AbeGDG5A (ORCPT ); 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!