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

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

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
>