Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754145Ab3FIQ1E (ORCPT ); Sun, 9 Jun 2013 12:27:04 -0400 Received: from cantor2.suse.de ([195.135.220.15]:40430 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751811Ab3FIQ1B (ORCPT ); Sun, 9 Jun 2013 12:27:01 -0400 Date: Sun, 9 Jun 2013 18:26:53 +0200 From: Borislav Petkov To: "Rafael J. Wysocki" Cc: Stratos Karafotis , Viresh Kumar , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , linux-pm@vger.kernel.org, cpufreq@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/3] cpufreq: ondemand: Change the calculation of target frequency Message-ID: <20130609162653.GA5004@pd.tnic> References: <1731097.2elXaGsAyC@vostro.rjw.lan> <51B394A9.3020005@semaphore.gr> <2892497.M93vsSKx5I@vostro.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <2892497.M93vsSKx5I@vostro.rjw.lan> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3721 Lines: 97 On Sun, Jun 09, 2013 at 12:18:09AM +0200, Rafael J. Wysocki wrote: > The average power drawn by the package is slightly higher with the > patchset applied (27.66 W vs 27.25 W), but since the time needed to > complete the workload with the patchset applied was shorter by about > 2.3 sec, the total energy used was less in the latter case (by about > 25.7 J if I'm not mistaken, or 1% relative). This means that in the > absence of a power limit between 27.25 W and 27.66 W it's better to > use the kernel with the patchset applied for that particular workload > from the performance and energy usage perspective. > > Good, hopefully that's going to be confirmed on other systems and/or > with other workloads. :-) Yep, I see similar results on my AMD F15h. So there's a register which tells you what the current energy consumption in Watts is and support for it is integrated in lm_sensors. I did one read per second, for the duration of the kernel build (10-r5 + tip), with and without the patch, and averaged out the results: without ======= 1. 158 samples, avg Watts: 116.915 2. 158 samples, avg Watts: 116.855 3. 158 samples, avg Watts: 116.737 4. 158 samples, avg Watts: 116.792 => 116.82475 avg Watts. with ==== 1. 157 samples, avg Watts: 116.496 2. 156 samples, avg Watts: 117.535 3. 156 samples, avg Watts: 118.174 4. 157 samples, avg Watts: 117.95 => 117.53875 avg Watts. So there's a slight raise in the average power consumption but the samples count drops by 1 or 2, which is consistent with the observed kernel build speedup of 1 or 2 seconds. perf doesn't show any significant difference with and without the patch but those are single runs only. without ======= Performance counter stats for 'make -j9': 1167856.647713 task-clock # 7.272 CPUs utilized 1,071,177 context-switches # 0.917 K/sec 52,844 cpu-migrations # 0.045 K/sec 43,600,721 page-faults # 0.037 M/sec 4,712,068,048,465 cycles # 4.035 GHz 1,181,730,064,794 stalled-cycles-frontend # 25.08% frontend cycles idle 243,576,229,438 stalled-cycles-backend # 5.17% backend cycles idle 2,966,369,010,209 instructions # 0.63 insns per cycle # 0.40 stalled cycles per insn 651,136,706,156 branches # 557.548 M/sec 34,582,447,788 branch-misses # 5.31% of all branches 160.599796045 seconds time elapsed with ==== Performance counter stats for 'make -j9': 1169278.095561 task-clock # 7.271 CPUs utilized 1,076,528 context-switches # 0.921 K/sec 53,284 cpu-migrations # 0.046 K/sec 43,598,610 page-faults # 0.037 M/sec 4,721,747,687,668 cycles # 4.038 GHz 1,182,301,583,422 stalled-cycles-frontend # 25.04% frontend cycles idle 248,675,448,161 stalled-cycles-backend # 5.27% backend cycles idle 2,967,419,684,598 instructions # 0.63 insns per cycle # 0.40 stalled cycles per insn 651,527,448,140 branches # 557.205 M/sec 34,560,656,638 branch-misses # 5.30% of all branches 160.811815170 seconds time elapsed -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- -- 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/