From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753314AbbIJPfZ (ORCPT ); Thu, 10 Sep 2015 11:35:25 -0400 Received: from mail.kernel.org ([198.145.29.136]:54412 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751760AbbIJPfV (ORCPT ); Thu, 10 Sep 2015 11:35:21 -0400 Date: Thu, 10 Sep 2015 12:35:15 -0300 From: Arnaldo Carvalho de Melo To: kan.liang@intel.com Cc: Jiri Olsa , Peter Zijlstra , luto@kernel.org, Ingo Molnar , Stephane Eranian , ak@linux.intel.com, mark.rutland@arm.com, adrian.hunter@intel.com, Namhyung Kim , linux-kernel@vger.kernel.org Subject: Re: [PATCH V9 1/6] perf,tools: introduce generic FEAT for CPU attributes Message-ID: <20150910153515.GD23511@kernel.org> References: <1441740769-61236-1-git-send-email-kan.liang@intel.com> <1441740769-61236-2-git-send-email-kan.liang@intel.com> <20150910135838.GX3475@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150910135838.GX3475@kernel.org> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Thu, Sep 10, 2015 at 10:58:38AM -0300, Arnaldo Carvalho de Melo escreveu: > Em Tue, Sep 08, 2015 at 03:32:44PM -0400, kan.liang@intel.com escreveu: > > This patch introduces generic FEAT for CPU attributes. For the patch > > set, we only need cpu max frequency. But it can be easily extented to > > support more other CPU attributes. > > The cpu max frequency is from the first online cpu. > Ok, but don't we have to do error handling? i.e. you are returning 0 for > any error in trying to read the cpu max freq, shouldn't we bail out > somewhere? > And please move this get_cpu_max_freq() thing out of the cpumap.[ch] > files, it is not even a need completely specific to perf tooling, there > must be somewhere in tools/lib/api/ (kernel APIs) where this fits, no? So, I've updated my perf/env branch with routines to do that, that uses infrastructure to read files from virtual dirs that was there plus a few I just introduced, in the same vein, I will update your patches to use them and put there as well, for your consideration. The HEAD there is the one below: - Arnaldo commit 2bc1fae4ed8a842f52dc374449d37c3ec1fa1986 Author: Arnaldo Carvalho de Melo Date: Thu Sep 10 12:20:14 2015 -0300 tools lib cpu: Introduce cpu.[ch] to read sysfs cpu related information E.g.: $ ./cpu__get_max_freq 3200000 It does that, as Kan's patch does, by looking at these files: $ cat /sys/devices/system/cpu/online 0-3 $ ./sysfs__read_ull devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq=3200000 $ I.e. find out the first online CPU, then read its cpufreq info. But do it in tools/lib/api/, so that other tools living code can use it, not just perf. Based-on-a-patch-by: Kan Liang Cc: Adrian Hunter Cc: Borislav Petkov Cc: David Ahern Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Link: http://lkml.kernel.org/n/tip-915v4cvxqplaub8qco66b9mv@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo diff --git a/tools/lib/api/Build b/tools/lib/api/Build index 3653965cf481..e8b8a23b9bf4 100644 --- a/tools/lib/api/Build +++ b/tools/lib/api/Build @@ -1,2 +1,3 @@ libapi-y += fd/ libapi-y += fs/ +libapi-y += cpu.o diff --git a/tools/lib/api/cpu.c b/tools/lib/api/cpu.c new file mode 100644 index 000000000000..8c6489356e3a --- /dev/null +++ b/tools/lib/api/cpu.c @@ -0,0 +1,18 @@ +#include + +#include "cpu.h" +#include "fs/fs.h" + +int cpu__get_max_freq(unsigned long long *freq) +{ + char entry[PATH_MAX]; + int cpu; + + if (sysfs__read_int("devices/system/cpu/online", &cpu) < 0) + return -1; + + snprintf(entry, sizeof(entry), + "devices/system/cpu/cpu%d/cpufreq/cpuinfo_max_freq", cpu); + + return sysfs__read_ull(entry, freq); +} diff --git a/tools/lib/api/cpu.h b/tools/lib/api/cpu.h new file mode 100644 index 000000000000..81e9d3955961 --- /dev/null +++ b/tools/lib/api/cpu.h @@ -0,0 +1,6 @@ +#ifndef __API_CPU__ +#define __API_CPU__ + +int cpu__get_max_freq(unsigned long long *freq); + +#endif /* __API_CPU__ */