Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756366AbXKBQfv (ORCPT ); Fri, 2 Nov 2007 12:35:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751480AbXKBQfn (ORCPT ); Fri, 2 Nov 2007 12:35:43 -0400 Received: from e4.ny.us.ibm.com ([32.97.182.144]:38848 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750983AbXKBQfn (ORCPT ); Fri, 2 Nov 2007 12:35:43 -0400 Message-ID: <472B51D1.7010708@linux.vnet.ibm.com> Date: Fri, 02 Nov 2007 22:05:29 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com Organization: IBM User-Agent: Thunderbird 1.5.0.13 (X11/20070824) MIME-Version: 1.0 To: Ingo Molnar CC: Peter Zijlstra , Andrew Morton , Linux Kernel Mailing List Subject: Re: [PATCH] Fix delay accounting regression References: <20071102142220.24166.49046.sendpatchset@balbir-laptop> <20071102155358.GA32116@elte.hu> In-Reply-To: <20071102155358.GA32116@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1425 Lines: 40 Ingo Molnar wrote: > * Balbir Singh wrote: > >> Fix the delay accounting regression introduced by commit >> 75d4ef16a6aa84f708188bada182315f80aab6fa. rq no longer has sched_info >> data associated with it. task_struct sched_info structure is used by >> delay accounting to provide back statistics to user space. > > no, this really is broken code. sched_clock() is not a generally > reliable time source so at a minimum the rq->clock fix i mentioned is > needed. What user-space tools are utilizing delay-accounting by the way? Applications I can think of are 1. iotop 2. Some typical applications are mentioned in https://ols2006.108.redhat.com/2007/Reprints/nagar-Reprint.pdf > We have most of this data available under SCHEDSTATS - how about > consolidating CONFIG_TASK_DELAY_ACCT into CONFIG_SCHEDSTATS? > > Ingo Yes, we do use schedstats - except for two cases that I know of? 1. To accumulate information in taskstats to share with user space (we copy the data from schedstats into taskstats) 2. We accumulate the data for dead threads in a thread group -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/