Re: [RFC PATCH 0/7] Share events between metrics

From: Jiri Olsa <jolsa@redhat.com>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@chromium.org>, Kajol Jain <kjain@linux.ibm.com>,
	Andi Kleen <ak@linux.intel.com>,
	John Garry <john.garry@huawei.com>,
	Jin Yao <yao.jin@linux.intel.com>,
	Kan Liang <kan.liang@linux.intel.com>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Kim Phillips <kim.phillips@amd.com>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	bpf@vger.kernel.org, linux-perf-users@vger.kernel.org,
	Stephane Eranian <eranian@google.com>
Subject: Re: [RFC PATCH 0/7] Share events between metrics
Date: Thu, 7 May 2020 15:49:39 +0200	[thread overview]
Message-ID: <20200507134939.GA2804092@krava> (raw)
In-Reply-To: <20200507081436.49071-1-irogers@google.com>

On Thu, May 07, 2020 at 01:14:29AM -0700, Ian Rogers wrote:
> Metric groups contain metrics. Metrics create groups of events to
> ideally be scheduled together. Often metrics refer to the same events,
> for example, a cache hit and cache miss rate. Using separate event
> groups means these metrics are multiplexed at different times and the
> counts don't sum to 100%. More multiplexing also decreases the
> accuracy of the measurement.
> 
> This change orders metrics from groups or the command line, so that
> the ones with the most events are set up first. Later metrics see if
> groups already provide their events, and reuse them if
> possible. Unnecessary events and groups are eliminated.
> 
> RFC because:
>  - without this change events within a metric may get scheduled
>    together, after they may appear as part of a larger group and be
>    multiplexed at different times, lowering accuracy - however, less
>    multiplexing may compensate for this.
>  - libbpf's hashmap is used, however, libbpf is an optional
>    requirement for building perf.
>  - other things I'm not thinking of.

hi,
I can't apply this, what branch/commit is this based on?

	Applying: perf expr: migrate expr ids table to libbpf's hashmap
	error: patch failed: tools/perf/tests/pmu-events.c:428
	error: tools/perf/tests/pmu-events.c: patch does not apply
	error: patch failed: tools/perf/util/expr.h:2
	error: tools/perf/util/expr.h: patch does not apply
	error: patch failed: tools/perf/util/expr.y:73
	error: tools/perf/util/expr.y: patch does not apply
	Patch failed at 0001 perf expr: migrate expr ids table to libbpf's hashmap

thanks,
jirka

> 
> Thanks!
> 
> Ian Rogers (7):
>   perf expr: migrate expr ids table to libbpf's hashmap
>   perf metricgroup: change evlist_used to a bitmap
>   perf metricgroup: free metric_events on error
>   perf metricgroup: always place duration_time last
>   perf metricgroup: delay events string creation
>   perf metricgroup: order event groups by size
>   perf metricgroup: remove duped metric group events
> 
>  tools/perf/tests/expr.c       |  32 ++---
>  tools/perf/tests/pmu-events.c |  22 ++--
>  tools/perf/util/expr.c        | 125 ++++++++++--------
>  tools/perf/util/expr.h        |  22 ++--
>  tools/perf/util/expr.y        |  22 +---
>  tools/perf/util/metricgroup.c | 242 +++++++++++++++++++++-------------
>  tools/perf/util/stat-shadow.c |  46 ++++---
>  7 files changed, 280 insertions(+), 231 deletions(-)
> 
> -- 
> 2.26.2.526.g744177e7f7-goog
> 