Messages in this thread | | | Date | Thu, 8 Sep 2016 13:25:02 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [RFCv4 0/7] arm_pmu/perf tools: play nicely with CPU PMU cpumasks |
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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
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