From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750807AbWGFUYo (ORCPT ); Thu, 6 Jul 2006 16:24:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750811AbWGFUYo (ORCPT ); Thu, 6 Jul 2006 16:24:44 -0400 Received: from ccerelbas03.cce.hp.com ([161.114.21.106]:3724 "EHLO ccerelbas03.cce.hp.com") by vger.kernel.org with ESMTP id S1750807AbWGFUYn (ORCPT ); Thu, 6 Jul 2006 16:24:43 -0400 Date: Thu, 6 Jul 2006 13:16:16 -0700 From: Stephane Eranian To: Chuck Ebbert <76306.1226@compuserve.com> Cc: Andi Kleen , linux-kernel Subject: Re: [PATCH 10/17] 2.6.17.1 perfmon2 patch for review: PMU context switch Message-ID: <20060706201616.GA10760@frankl.hpl.hp.com> Reply-To: eranian@hpl.hp.com References: <200607061333_MC3-1-C44C-96D1@compuserve.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200607061333_MC3-1-C44C-96D1@compuserve.com> User-Agent: Mutt/1.4.1i Organisation: HP Labs Palo Alto Address: HP Labs, 1U-17, 1501 Page Mill road, Palo Alto, CA 94304, USA. E-mail: eranian@hpl.hp.com Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Chuck, On Thu, Jul 06, 2006 at 01:30:14PM -0400, Chuck Ebbert wrote: > In-Reply-To: <20060704152857.GA6999@frankl.hpl.hp.com> > > On Tue, 4 Jul 2006 08:28:57 -0700, Stephan Eranian wrote: > > > Here is what I get on my dual 2.4GHz Opteron 250: > > > > booted with idle=halt > > $ pfmon --us-c -ecpu_clk_unhalted,interrupts_masked_cycles_with_interrupt_pending,interrupts_masked_cycles,cycles_no_fpu_ops_retired -k --system-wide -t 10 > > > > CPU0 11,356,210 CPU_CLK_UNHALTED > > CPU0 0 INTERRUPTS_MASKED_CYCLES_WITH_INTERRUPT_PENDING > > CPU0 3,836,107 INTERRUPTS_MASKED_CYCLES > > CPU0 23,910,784,532 CYCLES_NO_FPU_OPS_RETIRED > > CPU1 19,303,632 CPU_CLK_UNHALTED > > CPU1 0 INTERRUPTS_MASKED_CYCLES_WITH_INTERRUPT_PENDING > > CPU1 13,942,265 INTERRUPTS_MASKED_CYCLES > > CPU1 23,911,872,654 CYCLES_NO_FPU_OPS_RETIRED > > So it looks like your Opteron continues to count CYCLES_NO_FPU_OPS_RETIRED > at full clock speed even when halted. > Yes, it certainly looks like it, idling at full clock speed. But that's a server CPU! I think this may have to do with latency to get back to useful work. > My Turion appears to slow down to ~40 MHz when halted and counts those > events at that speed. Using idle=poll shows no slowdown, as expected, > and unhalted clocks equals cycles_no_fpu_ops_retired. > That's a mobile processor, so I would expect it to use more aggressive power-saving scheme while idle, at the cost of higher latency to get back to full speed. The good thing about this is that it was not too hard to figure out what is going using pfmon. Where you specifically looking for this? Is this a documented behavior of the Turion64? -- -Stephane