Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764534AbZD3QJU (ORCPT ); Thu, 30 Apr 2009 12:09:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763554AbZD3QI7 (ORCPT ); Thu, 30 Apr 2009 12:08:59 -0400 Received: from gw1.cosmosbay.com ([212.99.114.194]:55318 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756798AbZD3QI6 convert rfc822-to-8bit (ORCPT ); Thu, 30 Apr 2009 12:08:58 -0400 Message-ID: <49F9CCD0.2080005@cosmosbay.com> Date: Thu, 30 Apr 2009 18:07:44 +0200 From: Eric Dumazet User-Agent: Thunderbird 2.0.0.21 (Windows/20090302) MIME-Version: 1.0 To: Ingo Molnar CC: Christoph Lameter , linux kernel , Andi Kleen , David Miller , jesse.brandeburg@intel.com, netdev@vger.kernel.org, haoki@redhat.com, mchan@broadcom.com, davidel@xmailserver.org Subject: [BUG] perf_counter: change cpu frequencies References: <49F71B63.8010503@cosmosbay.com> <49F76174.6060009@cosmosbay.com> <49F767FD.2040205@cosmosbay.com> <49F76F6C.80005@cosmosbay.com> <49F77108.7060509@cosmosbay.com> <20090429091130.GA27857@elte.hu> <49F9821C.5010802@cosmosbay.com> <20090430115736.GA24349@elte.hu> <49F9B0F0.40306@cosmosbay.com> In-Reply-To: <49F9B0F0.40306@cosmosbay.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-1.6 (gw1.cosmosbay.com [0.0.0.0]); Thu, 30 Apr 2009 18:07:45 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1930 Lines: 73 Eric Dumazet a ?crit : > But if I use plain "perf stat -a sleep 10" > it seems I get wrong values again (16 G cycles/sec) for all next perf sessions > Well, I confirm all my cpus switched from 3GHz to 2GHz, after "perf stat -a sleep 10" (but "perf stat -e instructions -e cycles -a sleep 10" doesnt trigger this problem) Nothing logged, and /proc/cpuinfo stills reports 3 GHz frequencies # cat unit.c main() { int i; for (i = 0 ; i < 10000000; i++) getppid(); } # time ./unit real 0m0.818s user 0m0.289s sys 0m0.529s # perf stat -a sleep 10 2>/dev/null # time ./unit real 0m1.122s user 0m0.482s sys 0m0.640s # tail -n 27 /proc/cpuinfo processor : 7 vendor_id : GenuineIntel cpu family : 6 model : 23 model name : Intel(R) Xeon(R) CPU E5450 @ 3.00GHz stepping : 6 cpu MHz : 3000.102 cache size : 6144 KB physical id : 1 siblings : 1 core id : 3 cpu cores : 4 apicid : 7 initial apicid : 7 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 10 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe lm constant_tsc arch_perfmon pebs bts pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 lahf_lm tpr_shadow vnmi flexpriority bogomips : 6000.01 clflush size : 64 power management: # grep CPU_FREQ .config # CONFIG_CPU_FREQ is not set perf_counter seems promising, but still... needs some bug hunting :) Thank you -- 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/