From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932866AbcIHQZN (ORCPT ); Thu, 8 Sep 2016 12:25:13 -0400 Received: from mail.kernel.org ([198.145.29.136]:45772 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752826AbcIHQZL (ORCPT ); Thu, 8 Sep 2016 12:25:11 -0400 Date: Thu, 8 Sep 2016 13:25:02 -0300 From: Arnaldo Carvalho de Melo To: Mark Rutland Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, alexander.shishkin@linux.intel.com, jolsa@kernel.org, mingo@redhat.com, peterz@infradead.org, will.deacon@arm.com Subject: Re: [RFCv4 0/7] arm_pmu/perf tools: play nicely with CPU PMU cpumasks Message-ID: <20160908162502.GB4801@kernel.org> References: <1473330112-28528-1-git-send-email-mark.rutland@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1473330112-28528-1-git-send-email-mark.rutland@arm.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.7.0 (2016-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Thu, Sep 08, 2016 at 11:21:45AM +0100, Mark Rutland escreveu: > Hi, > > I'm trying to make the perf tool play better with PMUs in heterogeneous systems > (e.g. big.LITTLE), where there are several logical PMUs, each covering a subset > of CPUs. So I added 6/7 and 7/7 to my local perf/core branch, I think they can go before the others, Peter, do you want me to take the kernel parts as well? - Arnaldo > Currently perf-record doesn't work for these PMUs, unless forced to use > per-thread mmaps. In the absence of a cpumask, it tries to open events on CPUs > not supported by a PMU, and gives up. In the presence of a cpumask, it ends up > failing to mmap, as the evlist->cpus map contains a different set of CPUs from > the evsel->cpus map populated from the cpumask. This is addressed by the > penultimate patch in this series. > > Complicating matters, prior to commit 00e727bb389359c8 ("perf stat: Balance > opening and reading events"), from version two of this series, perf-stat would > behave erroneously in the presence of a cpumask file, blocking forever after > the workload completed. While this is now fixed, existing binaries (e.g. those > shipped by distributions) would be broken by the addition of a cpumask file > kernel-side. > > To cater for this, this series adds support for a new PMU sysfs file, named > 'cpus' rather than 'cpumask', listing a number of CPUs that a logical PMU > covers. As old binaries will not look for this, this can be safely added to the > kernel without risk of breakage. > > I've included the kernel and userspace parts in this series as they've proven > difficult to review in isolation. > > Thanks, > Mark. > > Since v1 [1]: > * Avoid double cpu_map__idx() call in perf_evlist__mmap_per_evsel > * Look for a supported_cpumask file when a cpumask file is not present > > Since v2 [2]: > * Drop patches which have been picked up from v2 > * Rebase to v4.8-rc1 > * Better describe the issue in the supported_cpumask patch > > Since v3 [3]: > * Prepend patches exporting the cpus file for ARM PMUs > * s/supported_cpus/cpus/ > > [1] http://lkml.kernel.org/r/1467907474-3290-1-git-send-email-mark.rutland@arm.com > [2] http://lkml.kernel.org/r/1468577293-19667-1-git-send-email-mark.rutland@arm.com > [3] http://lkml.kernel.org/r/1470933366-1364-1-git-send-email-mark.rutland@arm.com > > Mark Rutland (7): > drivers/perf: arm_pmu: add common attr group fields > arm64: perf: move to common attr_group fields > arm: perf: move to common attr_group fields > drivers/perf: arm_pmu: only use common attr_groups > drivers/perf: arm_pmu: expose a cpumask in sysfs > perf: util: only open events on CPUs an evsel permits > perf: util: support alternative sysfs cpumask > > arch/arm/kernel/perf_event_v7.c | 47 ++++++++++++++++++++++++----------------- > arch/arm64/kernel/perf_event.c | 36 ++++++++++++++++++++----------- > drivers/perf/arm_pmu.c | 23 ++++++++++++++++++++ > include/linux/perf/arm_pmu.h | 10 ++++++++- > tools/perf/util/evlist.c | 8 ++++++- > tools/perf/util/pmu.c | 15 ++++++++++--- > 6 files changed, 103 insertions(+), 36 deletions(-) > > -- > 1.9.1