From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29129 invoked by alias); 17 Mar 2006 17:10:59 -0000 Received: (qmail 29120 invoked by uid 22791); 17 Mar 2006 17:10:59 -0000 X-Spam-Status: No, hits=-1.0 required=5.0 tests=BAYES_05,FORGED_RCVD_HELO X-Spam-Check-By: sourceware.org Received: from 209-166-240-202.cust.walrus.com (HELO mail1.telemetry-investments.com) (209.166.240.202) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 17 Mar 2006 17:10:57 +0000 Received: from ti64.telemetry-investments.com (ti64 [192.168.8.64]) by ti41.telemetry-investments.com (Postfix) with ESMTP id F3C5F100EC; Fri, 17 Mar 2006 12:10:53 -0500 (EST) Received: by ti64.telemetry-investments.com (Postfix, from userid 343) id ED5C9FF98; Fri, 17 Mar 2006 12:10:53 -0500 (EST) Date: Fri, 17 Mar 2006 17:10:00 -0000 From: "Bill Rugolsky Jr." To: William Cohen Cc: "Frank Ch. Eigler" , systemtap@sources.redhat.com Subject: Re: Proposed systemtap access to perfmon hardware Message-ID: <20060317171053.GA31131@ti64.telemetry-investments.com> References: <44183FCF.6010809@redhat.com> <441AE1DE.2040207@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <441AE1DE.2040207@redhat.com> User-Agent: Mutt/1.4.1i X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2006-q1/txt/msg00822.txt.bz2 On Fri, Mar 17, 2006 at 11:20:46AM -0500, William Cohen wrote: > To try to get a feel on how the performance monitoring hardware support > would work in SystemTap I wrote some simple examples. Below are examples > for computing IPC, average cycle count, and sampling within a function. > The IPC and average cycle count function need a bit of rework to work > for a SMP machines. > > Let me know if there are comments or questions on the examples. A non-statistical application for systemtap perfctrs: In light of a suggestion made by Alan Cox yesterday, http://lkml.org/lkml/2006/3/16/118 I'm hacking up some additions to Ingo Molnar's latency tracing patch that will track retired insns as well as clock cycles, so I can see where the processor is stalled on I/O, SMM traps, etc., within a given execution path. For the particular case that triggered the aforementioned thread, I know the precise offending instruction, but in the general case a search for the culprit might be necessary, and doing this with systemtap would be convenient. Regards, Bill Rugolsky