From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750864AbWFFBAE (ORCPT ); Mon, 5 Jun 2006 21:00:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750891AbWFFBAE (ORCPT ); Mon, 5 Jun 2006 21:00:04 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]:36759 "EHLO e31.co.us.ibm.com") by vger.kernel.org with ESMTP id S1750864AbWFFBAB (ORCPT ); Mon, 5 Jun 2006 21:00:01 -0400 Message-ID: <4484D25E.4020805@in.ibm.com> Date: Tue, 06 Jun 2006 06:24:54 +0530 From: Balbir Singh Reply-To: balbir@in.ibm.com Organization: IBM India Private Limited User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051205 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Jay Lan , Peter Chubb Subject: Merge of per task delay accounting (was Re: 2.6.18 -mm merge plans) References: <20060604135011.decdc7c9.akpm@osdl.org> In-Reply-To: <20060604135011.decdc7c9.akpm@osdl.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > per-task-delay-accounting-setup.patch > per-task-delay-accounting-setup-fix-1.patch > per-task-delay-accounting-setup-fix-2.patch > per-task-delay-accounting-sync-block-i-o-and-swapin-delay-collection.patch > per-task-delay-accounting-sync-block-i-o-and-swapin-delay-collection-fix-1.patch > per-task-delay-accounting-cpu-delay-collection-via-schedstats.patch > per-task-delay-accounting-cpu-delay-collection-via-schedstats-fix-1.patch > per-task-delay-accounting-utilities-for-genetlink-usage.patch > per-task-delay-accounting-taskstats-interface.patch > per-task-delay-accounting-taskstats-interface-fix-1.patch > per-task-delay-accounting-taskstats-interface-fix-2.patch > per-task-delay-accounting-delay-accounting-usage-of-taskstats-interface.patch > per-task-delay-accounting-delay-accounting-usage-of-taskstats-interface-use-portable-cputime-api-in-__delayacct_add_tsk.patch > per-task-delay-accounting-documentation.patch > per-task-delay-accounting-proc-export-of-aggregated-block-i-o-delays.patch > per-task-delay-accounting-proc-export-of-aggregated-block-i-o-delays-warning-fix.patch > > I just don't know. There are a number of groups who pop up with various > enhanced accounting requirements and patches (all quite different) but I > haven't heard a lot of enthusiasm from any of them over this work, which > attempts to provide an extensible framework for accumulation and querying > of per-task metrics. > > But then again, we cannot just sit there and wait for everyone to be 100% > happy. So I'm 51% inclined to push this along. > > Anyone else who has an interest in this sort of thing needs to be aware > that there will be an expectation that any future statistics submissions > should use these interfaces. So the time to pay attention is right now. > Hi, Andrew, Here is a brief summary of the status of the response we have received from the stakeholders (some of it has been duplicated in previous postings) Project Response 1. CSA accounting/PAGG/JOB: Has agreed to use taskstats Jay Lan interface 2. per-process IO statistics: None Levent Serinol Needs are subset of CSA 3. per-cpu time statistics: None (email bounced) Erich Focht Needs can be met by taskstats Statistics not yet submitted 4. Microstate accounting: None Peter Chubb overlap with delay accounting prefers /proc due to convenience taskstats can meet the needs 5. ELSA: Guillaume Thouvenin None ELSA is not a direct user of new kernel statistics Consumer of CSA/BSD accounting statistics 6. pnotify: Jes Sorensen None (taken over pnotify from Erik Jacobson) Informed over private email that pnotify replacement is being worked on. pnotify or its replacement will not be concerned with exporting data to user space or collecting any statistics. 7. Scalable statistics counters with /proc Not working on it reporting: anymore Ravikiran G Thirumalai, Dipankar Sarma Studying the responses from all stake holders, Jay Lan's was the most encouraging. Peter Chubb prefers the /proc interface due to the text interface and ease of parsing. (in our opinion, taskstats can meet the needs easily and the getdelays utility can provide the same ease for parsing). The others did not respond. Some performance numbers of taskstats were posted at http://lkml.org/lkml/2006/3/23/141. The result highlights are included below Results highlights - Configuring delay accounting adds < 0.5% overhead in most cases and even reduces overhead in some cases - Enabling delay accounting has similar results with a maximum overhead of 1.2% for hackbench, most other overheads < 1% and reduction in overhead in some cases These statistics are _per task_ and can be extended easily by anyone who wishes to obtain per task data. An example of per task improved scheduler statistics was mentioned in http://lkml.org/lkml/2006/6/1/381 (I am not sure if the email refers to our per-task statistics). If not, the new statistics could easily use the taskstats interface. These statistics can be used by software product stacks to monitor usage information about the various tasks they create and control. I also informally spoke to a group of students (verbally), who were excited at the possibility of using the per-task statistics to do dynamic deadline based power management. They want to use the delay data (CPU and IO) to predict deadlines for a task and then use these results for dynamically scaling CPU frequency. The ability to monitor the CPU run and delay data and IO delay data is useful. I would request you to consider the inclusion per-task delay accounting into 2.6.18. -- Thanks, Balbir Singh, Linux Technology Center, IBM Software Labs