Messages in this thread | | | From | Arnaldo Carvalho de Melo <> | Date | Tue, 10 Mar 2020 15:04:23 -0300 | Subject | Re: [PATCH V2 0/5] Support metric group constraint |
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Em Wed, Feb 26, 2020 at 04:35:49PM +0100, Jiri Olsa escreveu: > On Mon, Feb 24, 2020 at 01:59:19PM -0800, kan.liang@linux.intel.com wrote: > > From: Kan Liang <kan.liang@linux.intel.com> > > > > Changes since V1: > > - Remove global static flag violate_nmi_constraint, and add a new > > function metricgroup___watchdog_constraint_hint() for all > > watchdog constraint hints in patch 4. > > The rest of the patches are not changed. > > Acked-by: Jiri Olsa <jolsa@redhat.com>
Thanks, tested, applied,
- Arnaldo
> thanks, > jirka > > > > > Some metric groups, e.g. Page_Walks_Utilization, will never count when > > NMI watchdog is enabled. > > > > $echo 1 > /proc/sys/kernel/nmi_watchdog > > $perf stat -M Page_Walks_Utilization > > > > Performance counter stats for 'system wide': > > > > <not counted> itlb_misses.walk_pending (0.00%) > > <not counted> dtlb_load_misses.walk_pending (0.00%) > > <not counted> dtlb_store_misses.walk_pending (0.00%) > > <not counted> ept.walk_pending (0.00%) > > <not counted> cycles (0.00%) > > > > 2.343460588 seconds time elapsed > > > > Some events weren't counted. Try disabling the NMI watchdog: > > echo 0 > /proc/sys/kernel/nmi_watchdog > > perf stat ... > > echo 1 > /proc/sys/kernel/nmi_watchdog > > The events in group usually have to be from the same PMU. Try > > reorganizing the group. > > > > A metric group is a weak group, which relies on group validation > > code in the kernel to determine whether to be opened as a group or > > a non-group. However, group validation code may return false-positives, > > especially when NMI watchdog is enabled. (The metric group is allowed > > as a group but will never be scheduled.) > > > > The attempt to fix the group validation code has been rejected. > > https://lore.kernel.org/lkml/20200117091341.GX2827@hirez.programming.kicks-ass.net/ > > Because we cannot accurately predict whether the group can be scheduled > > as a group, only by checking current status. > > > > This patch set provides another solution to mitigate the issue. > > Add "MetricConstraint" in event list, which provides a hint for perf tool, > > e.g. "MetricConstraint": "NO_NMI_WATCHDOG". Perf tool can change the > > metric group to non-group (standalone metrics) if NMI watchdog is enabled. > > > > After applying the patch, > > > > $echo 1 > /proc/sys/kernel/nmi_watchdog > > $perf stat -M Page_Walks_Utilization > > Splitting metric group Page_Walks_Utilization into standalone metrics. > > Try disabling the NMI watchdog to comply NO_NMI_WATCHDOG metric constraint: > > echo 0 > /proc/sys/kernel/nmi_watchdog > > perf stat ... > > echo 1 > /proc/sys/kernel/nmi_watchdog > > > > Performance counter stats for 'system wide': > > > > 18,253,454 itlb_misses.walk_pending # 0.0 > > Page_Walks_Utilization (50.55%) > > 78,051,525 dtlb_load_misses.walk_pending (50.55%) > > 29,213,063 dtlb_store_misses.walk_pending (50.55%) > > 0 ept.walk_pending (50.55%) > > 2,542,132,364 cycles (49.92%) > > > > 1.037095993 seconds time elapsed > > > > Kan Liang (5): > > perf jevents: Support metric constraint > > perf metricgroup: Factor out metricgroup__add_metric_weak_group() > > perf util: Factor out sysctl__nmi_watchdog_enabled() > > perf metricgroup: Support metric constraint > > perf vendor events: Add NO_NMI_WATCHDOG metric constraint > > > > .../arch/x86/cascadelakex/clx-metrics.json | 3 +- > > .../pmu-events/arch/x86/skylake/skl-metrics.json | 3 +- > > .../pmu-events/arch/x86/skylakex/skx-metrics.json | 3 +- > > tools/perf/pmu-events/jevents.c | 19 ++-- > > tools/perf/pmu-events/jevents.h | 2 +- > > tools/perf/pmu-events/pmu-events.h | 1 + > > tools/perf/util/metricgroup.c | 109 ++++++++++++++++----- > > tools/perf/util/stat-display.c | 6 +- > > tools/perf/util/util.c | 18 ++++ > > tools/perf/util/util.h | 2 + > > 10 files changed, 128 insertions(+), 38 deletions(-) > > > > -- > > 2.7.4 > > >
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- Arnaldo
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