Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756563AbXI1TvU (ORCPT ); Fri, 28 Sep 2007 15:51:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752624AbXI1TvK (ORCPT ); Fri, 28 Sep 2007 15:51:10 -0400 Received: from mx1.redhat.com ([66.187.233.31]:46410 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752726AbXI1TvI (ORCPT ); Fri, 28 Sep 2007 15:51:08 -0400 To: Mathieu Desnoyers Cc: Nick Piggin , Ingo Molnar , Andrew Morton , Fengguang Wu , hirofumi@mail.parknet.co.jp, galak@kernel.crashing.org, zaitcev@redhat.com, greg@kroah.com, Linus Torvalds , linux-kernel@vger.kernel.org, mbligh@google.com Subject: Re: [PATCH] writeback: remove unnecessary wait in throttle_vm_writeout() References: <390857819.00313@ustc.edu.cn> <20070928080202.GA10293@elte.hu> <20070928162347.GA11024@Krystal> <200709281010.28086.nickpiggin@yahoo.com.au> <20070928175756.GA16066@Krystal> From: fche@redhat.com (Frank Ch. Eigler) Date: Fri, 28 Sep 2007 15:50:14 -0400 In-Reply-To: <20070928175756.GA16066@Krystal> (Mathieu Desnoyers's message of "Fri, 28 Sep 2007 13:57:56 -0400") Message-ID: User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1001 Lines: 26 Mathieu Desnoyers writes: >> [...] >> > I totally agree with Ingo here. Having a basic instrumentation that is >> > enabled by default will help to identify code paths causing unexpected >> > delays in the kernel. [...] > >> It is. See: CONFIG_VM_EVENT_COUNTERS and all the other vm specific >> crap littered in /proc/ (buddyinfo, zoneinfo, meminfo, etc). [...] > Isn't the actual instrumentation present in the VM subsystem > consisting mostly of event counters ? This kind of profiling > provides limited help in following specific delays in the > kernel. [...] These existing VM events/counters could be a good target for a second worked-out example (after blktrace) of reimplementation using generic markers. - FChE - 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/