Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754900Ab0HXLiJ (ORCPT ); Tue, 24 Aug 2010 07:38:09 -0400 Received: from e5.ny.us.ibm.com ([32.97.182.145]:34706 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751470Ab0HXLiH (ORCPT ); Tue, 24 Aug 2010 07:38:07 -0400 Date: Tue, 24 Aug 2010 17:08:01 +0530 From: Balbir Singh To: Peter Zijlstra Cc: Venkatesh Pallipadi , Martin Schwidefsky , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , Paul Menage , linux-kernel@vger.kernel.org, Paul Turner , Heiko Carstens , Paul Mackerras , Tony Luck Subject: Re: [PATCH 0/4] Finer granularity and task/cgroup irq time accounting Message-ID: <20100824113801.GO4684@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <1279583835-22854-1-git-send-email-venki@google.com> <20100720095546.2f899e04@mschwide.boeblingen.de.ibm.com> <20100722131239.208d9501@mschwide.boeblingen.de.ibm.com> <1282636286.2605.2307.camel@laptop> <20100824080515.GK4684@balbir.in.ibm.com> <1282640953.2605.2428.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1282640953.2605.2428.camel@laptop> User-Agent: Mutt/1.5.20 (2009-12-10) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1255 Lines: 35 * Peter Zijlstra [2010-08-24 11:09:13]: > > > > cgroup level info does make sense, assuming that tasks that share the > > costs being mentioned here belong to the same cgroup. > > I don't think that's a valid assumption. > > If its not true for tasks, then its not true for groups of tasks either. > It might be slightly less wrong due to the larger number of entities > reducing the error bounds, but its still wrong in principle. > The point is for containers it is more likely to give the right answer and so on. Yes, the results are not 100% accurate. > The whole attribution mess can only be solved by actually splitting out > the entries that do work, like per-cgroup workqueue threads and similar > things. > > System wide entities like IRQs are very hard to attribute correctly like > Martin already argued, and I don't think its worth doing. I see Martin's view point, is the suggestion then that we amortize these costs across all tasks? -- Three Cheers, Balbir -- 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/