From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751881AbcGRQiW (ORCPT ); Mon, 18 Jul 2016 12:38:22 -0400 Received: from foss.arm.com ([217.140.101.70]:59430 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751575AbcGRQiU (ORCPT ); Mon, 18 Jul 2016 12:38:20 -0400 Subject: Re: [RFCv2 4/4] perf: util: support sysfs supported_cpumask file To: Mark Rutland , linux-kernel@vger.kernel.org References: <1468577293-19667-1-git-send-email-mark.rutland@arm.com> <1468577293-19667-5-git-send-email-mark.rutland@arm.com> Cc: acme@kernel.org, adrian.hunter@intel.com, alexander.shishkin@linux.intel.com, hekuang@huawei.com, jolsa@kernel.org, kan.liang@intel.com, mingo@redhat.com, peterz@infradead.org, wangnan0@huawei.com From: Suzuki K Poulose Message-ID: Date: Mon, 18 Jul 2016 17:38:16 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <1468577293-19667-5-git-send-email-mark.rutland@arm.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/07/16 11:08, Mark Rutland wrote: > For system PMUs, the perf tools have long expected a cpumask file under > sysfs, describing the single CPU which they support events being > opened/handled on. Prior patches in this series have reworked this > support to support multiple CPUs in a mask, as is required to handle > heterogeneous CPU PMUs. > > Unfortunately, adding a cpumask file to CPU PMUs would break existing > userspace. Prior to this series, perf record will refuse to open events, > and perf stat may unexpectedly block at exit time. In the absence of a > cpumask, perf stat is functional. > > To address this, this patch adds support for a new file, > supported_cpumask, which can be used to describe heterogeneous CPUs, > without the risk of breaking existing userspace binaries. > > Signed-off-by: Mark Rutland > --- > tools/perf/util/pmu.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c > index ddb0261..06c985c 100644 > --- a/tools/perf/util/pmu.c > +++ b/tools/perf/util/pmu.c > @@ -445,14 +445,23 @@ static struct cpu_map *pmu_cpumask(const char *name) > FILE *file; > struct cpu_map *cpus; > const char *sysfs = sysfs__mountpoint(); > + const char *path_template[] = { > + "%s/bus/event_source/devices/%s/cpumask", > + "%s/bus/event_source/devices/%s/supported_cpumask", > + NULL > + }; > + unsigned int i; > > if (!sysfs) > return NULL; > > - snprintf(path, PATH_MAX, > - "%s/bus/event_source/devices/%s/cpumask", sysfs, name); > + for (i = 0; i < ARRAY_SIZE(path_template); i++) { The check could be "path_template[i]" to avoid an iteration with NULL template. > + snprintf(path, PATH_MAX, *path_template, sysfs, name); Btw, did you mean to use path_template[i] here instead of *path_template ? > + if (stat(path, &st) == 0) > + break; > + } > > - if (stat(path, &st) < 0) > + if (!*path_template) Same here ? > return NULL; Suzuki