From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751478AbWFPQVk (ORCPT ); Fri, 16 Jun 2006 12:21:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751480AbWFPQVj (ORCPT ); Fri, 16 Jun 2006 12:21:39 -0400 Received: from mx1.redhat.com ([66.187.233.31]:6354 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1751478AbWFPQVj (ORCPT ); Fri, 16 Jun 2006 12:21:39 -0400 Date: Fri, 16 Jun 2006 12:18:06 -0400 From: "Frank Ch. Eigler" To: Christoph Hellwig , eranian@hpl.hp.com, linux-kernel@vger.kernel.org, systemtap@sources.redhat.com, wcohen@redhat.com, perfmon@napali.hpl.hp.com Subject: Re: [PATCH 9/16] 2.6.17-rc6 perfmon2 patch for review: kernel-level API support (kapi) Message-ID: <20060616161806.GI30867@redhat.com> References: <200606150907.k5F97coF008178@frankl.hpl.hp.com> <20060616135014.GB12657@infradead.org> <20060616140234.GI10034@frankl.hpl.hp.com> <20060616154519.GA28931@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060616154519.GA28931@infradead.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi - > > Whether one uses systemtap, raw kprobes, or some specialized > > tracing/stats-collecting patch surely forthcoming, kernel-level APIs > > would be needed to perform fine-grained kernel-scope measurements > > using these counters. > > No, there's not need to add kernel bloat for performance monitoring. > This kind of stuff shoul dabsolutely be done from userspace. Userspace measurements provide only large-grained quantities. Can you argue convincingly that there is never a need to measure focused quantities such as cache behaviors of individual subsystems, branch prediction statistics of a new algorithm? That running system-level benchmarks is the most efficient way for developers to assess their changes? That the scheduler would not benefit from access to HT resource utilization statistics? All these sorts of efforts seem to require a kernel-side perfmon API. - FChE