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

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Message-ID: <20250410044532.52017-1-irogers@google.com>
Date: Wed,  9 Apr 2025 21:45:29 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, 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: [PATCH v1 0/3] Metric related performance improvements

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
```

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