From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751291AbWGKPdv (ORCPT ); Tue, 11 Jul 2006 11:33:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751294AbWGKPdv (ORCPT ); Tue, 11 Jul 2006 11:33:51 -0400 Received: from e5.ny.us.ibm.com ([32.97.182.145]:43179 "EHLO e5.ny.us.ibm.com") by vger.kernel.org with ESMTP id S1751291AbWGKPdu (ORCPT ); Tue, 11 Jul 2006 11:33:50 -0400 Message-ID: <44B3C4D6.8010606@watson.ibm.com> Date: Tue, 11 Jul 2006 11:33:42 -0400 From: Shailabh Nagar User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Christoph Hellwig CC: Andrew Morton , linux-kernel , Jay Lan , Chris Sturtivant , Paul Jackson , Balbir Singh , Chandra Seetharaman Subject: Re: [Patch 0/6] delay accounting & taskstats fixes References: <1152591838.14142.114.camel@localhost.localdomain> <20060711112835.GA22832@infradead.org> In-Reply-To: <20060711112835.GA22832@infradead.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Christoph Hellwig wrote: > On Tue, Jul 11, 2006 at 12:23:58AM -0400, Shailabh Nagar wrote: > >>Andrew, >> >>Chandra, Balbir & I have been putting taskstats and delay accounting >>patches through some extensive testing on multiple platforms. >> >>Following are a set of patches that fix some bugs found as well as >>some cleanups of the code. Some results showing the cpumask feature >>works as expected will follow separately. > > > Btw, did you ever explain what this delay accounting code is useful for > exactly? Yes. Previous postings have explained the rationale, http://www.uwsg.indiana.edu/hypermail/linux/kernel/0511.1/2275.html http://www.uwsg.indiana.edu/hypermail/linux/kernel/0512.0/2152.html lwn.net had a good summary as always, http://lwn.net/Articles/173209/ > It's an awfull lot of code that doesn't seem to have a huge > use. The delay accounting part of the code is quite small (just a few lines of timestamping code place in core kernel code) and much of the remaining size comes from the interface. Since the interface is designed to be of generic use towards ANY per-task accounting needs, discussions and code have been fairly involved. We went through a long discussion of potential exploiters: (see thread under [Patch 0/8] per-task delay accounting at http://www.uwsg.indiana.edu/hypermail/linux/kernel/0603.3/index.html > While we're at it do you have a pointer to the associated userspace code? > Its part of the patches in Documentation/accounting/getdelays.c and the last-but-one version of it can be viewed at its location in the -mm tree: http://www.linux-m32r.org/lxr/http/source/Documentation/accounting/?a=generic (The just accepted patches updates the documentation especially the parts relating to cpumasks but the above should also suffice to give a flavor of what userspace could do). Thanks, Shailabh