From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Thu, 8 Sep 2016 11:21:45 +0100 Subject: [RFCv4 0/7] arm_pmu/perf tools: play nicely with CPU PMU cpumasks Message-ID: <1473330112-28528-1-git-send-email-mark.rutland@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. 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 at arm.com [2] http://lkml.kernel.org/r/1468577293-19667-1-git-send-email-mark.rutland at arm.com [3] http://lkml.kernel.org/r/1470933366-1364-1-git-send-email-mark.rutland at 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