linux-kernel - Re: [PATCH v1 0/3] Metric related performance improvements

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Message-ID: <Z_dp7E2wtSek-KHo@z2>
Date: Wed, 9 Apr 2025 23:49:16 -0700
From: Namhyung Kim <namhyung@...nel.org>
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>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	James Clark <james.clark@...aro.org>, Xu Yang <xu.yang_2@....com>,
	John Garry <john.g.garry@...cle.com>,
	Dominique Martinet <asmadeus@...ewreck.org>,
	Thomas Richter <tmricht@...ux.ibm.com>,
	Weilin Wang <weilin.wang@...el.com>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 0/3] Metric related performance improvements

Hi Ian,

On Wed, Apr 09, 2025 at 09:45:29PM -0700, Ian Rogers wrote:
> The "PMU JSON event tests" have been running slowly, these changes
> target improving them with an improvement of the test running 8 to 10
> times faster.
> 
> The first patch changes from searching through all aliases by name in
> a list to using a hashmap. Doing a fast hashmap__find means testing
> for having an event needn't load from disk if an event is already
> present.
> 
> The second patch switch the fncache to use a hashmap rather than its
> own hashmap with a limited number of buckets. When there are many
> filename queries, such as with a test, there are many collisions with
> the previous fncache approach leading to linear searching of the
> entries.
> 
> The final patch adds a find function for metrics. Normally metrics can
> match by name and group, however, only name matching happens when one
> metric refers to another. As we test every "id" in a metric to see if
> it is a metric, the find function can dominate performance as it
> linearly searches all metrics. Add a find function for the metrics
> table so that a metric can be found by name with a binary search.
> 
> Before these changes:
> ```
> $ time perf test -v 10
>  10: PMU JSON event tests                                            :
>  10.1: PMU event table sanity                                        : Ok
>  10.2: PMU event map aliases                                         : Ok
>  10.3: Parsing of PMU event table metrics                            : Ok
>  10.4: Parsing of PMU event table metrics with fake PMUs             : Ok
>  10.5: Parsing of metric thresholds with fake PMUs                   : Ok
> 
> real    0m18.499s
> user    0m18.150s
> sys     0m3.273s
> ```
> 
> After these changes:
> ```
> $ time perf test -v 10
>  10: PMU JSON event tests                                            :
>  10.1: PMU event table sanity                                        : Ok
>  10.2: PMU event map aliases                                         : Ok
>  10.3: Parsing of PMU event table metrics                            : Ok
>  10.4: Parsing of PMU event table metrics with fake PMUs             : Ok
>  10.5: Parsing of metric thresholds with fake PMUs                   : Ok
> 
> real    0m2.338s
> user    0m1.797s
> sys     0m2.186s
> ```

Great, I also see the speedup on my machine from 32s to 3s.

Tested-by: Namhyung Kim <namhyung@...nel.org>

Thanks,
Namhyung

> 
> Ian Rogers (3):
>   perf pmu: Change aliases from list to hashmap
>   perf fncache: Switch to using hashmap
>   perf metricgroup: Binary search when resolving referred to metrics
> 
>  tools/perf/builtin-stat.c                |   6 +-
>  tools/perf/pmu-events/empty-pmu-events.c |  66 ++++++++-
>  tools/perf/pmu-events/jevents.py         |  66 ++++++++-
>  tools/perf/pmu-events/pmu-events.h       |  23 +++-
>  tools/perf/tests/pmu-events.c            | 129 +++++++++--------
>  tools/perf/util/fncache.c                |  69 +++++-----
>  tools/perf/util/fncache.h                |   1 -
>  tools/perf/util/hwmon_pmu.c              |  43 +++---
>  tools/perf/util/metricgroup.c            | 102 ++++++--------
>  tools/perf/util/metricgroup.h            |   2 +-
>  tools/perf/util/pmu.c                    | 167 +++++++++++++++--------
>  tools/perf/util/pmu.h                    |   4 +-
>  tools/perf/util/srccode.c                |   4 +-
>  tools/perf/util/tool_pmu.c               |  17 +--
>  14 files changed, 430 insertions(+), 269 deletions(-)
> 
> -- 
> 2.49.0.504.g3bcea36a83-goog
>