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[179.240.149.111]) by smtp.gmail.com with ESMTPSA id g3sm8980446qke.89.2020.03.10.11.04.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Mar 2020 11:04:27 -0700 (PDT) From: Arnaldo Carvalho de Melo X-Google-Original-From: Arnaldo Carvalho de Melo Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id D7CC740009; Tue, 10 Mar 2020 15:04:23 -0300 (-03) Date: Tue, 10 Mar 2020 15:04:23 -0300 To: Jiri Olsa Cc: kan.liang@linux.intel.com, mingo@redhat.com, peterz@infradead.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, namhyung@kernel.org, ravi.bangoria@linux.ibm.com, yao.jin@linux.intel.com, ak@linux.intel.com Subject: Re: [PATCH V2 0/5] Support metric group constraint Message-ID: <20200310180423.GL15931@kernel.org> References: <1582581564-184429-1-git-send-email-kan.liang@linux.intel.com> <20200226153549.GD217283@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200226153549.GD217283@krava> X-Url: http://acmel.wordpress.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > > > > 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 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': > > > > itlb_misses.walk_pending (0.00%) > > dtlb_load_misses.walk_pending (0.00%) > > dtlb_store_misses.walk_pending (0.00%) > > ept.walk_pending (0.00%) > > 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 > > > -- - Arnaldo