Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759067AbZGCVbg (ORCPT ); Fri, 3 Jul 2009 17:31:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757219AbZGCVb3 (ORCPT ); Fri, 3 Jul 2009 17:31:29 -0400 Received: from smtpauth01.csee.onr.siteprotect.com ([64.26.60.145]:39264 "EHLO smtpauth01.csee.onr.siteprotect.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756365AbZGCVb2 (ORCPT ); Fri, 3 Jul 2009 17:31:28 -0400 Date: Fri, 3 Jul 2009 17:43:12 -0400 (EDT) From: Vince Weaver X-X-Sender: vince@pianoman.cluster.toy To: Ingo Molnar cc: Peter Zijlstra , Paul Mackerras , linux-kernel@vger.kernel.org, Mike Galbraith Subject: Re: [numbers] perfmon/pfmon overhead of 17%-94% In-Reply-To: <20090703075822.GA13505@elte.hu> Message-ID: References: <20090624151010.GA12799@elte.hu> <20090627060432.GB16200@elte.hu> <20090627064404.GA19368@elte.hu> <20090629210206.GB13125@elte.hu> <20090703075822.GA13505@elte.hu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1909 Lines: 37 On Fri, 3 Jul 2009, Ingo Molnar wrote: > That would give a mixture of hardware and software counter based IRQ > instrumentation features that looks quite compelling. Any comments > on what features/capabilities you'd like to see in this area? I'm mainly interested in just an aggregate total of "this many interrupts occurred". It wouldn't even need to be separated out by type or number. I don't know if the metric would be useful to anyone else. I tried to hack this up a long time ago, to have the result reported with rusage() but never got anywhere with it. > Btw., perfcounters still has no support for older Intel CPUs such as > P3's and P2's - and they have pretty sane PMUs - so if you have such > a machine (which your perfmon contribution suggests you might > have/had) and are interested it would be nice to get support for > them. P4 support is interesting too but more challenging. I was indeed the one who got perfmon2 running on Pentium Pro, Pentium II, and MIPS R12k. For all those though there was an existing PMU driver and I just added the appropriate "case" statements to enable support, and then provided an updated list of available counters to the userspace utility. The only real kernel hacking involved was the week spent tracking down a hard-to-debug interrupt issue on the MIPS machine. Unfortunately I think writing PMU drivers is a bit beyond me, for the amount of time I have. Especially as the relevant machines I have are located in relatively inaccessible locations (and PMU mistakes can lock up the machines) plus it can take the better part of a day to compile 2.6 kernels on some of those machines. Vince -- 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/