From: Ian Rogers <irogers@google.com>
To: 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>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
Jin Yao <yao.jin@linux.intel.com>,
John Garry <john.garry@huawei.com>, Paul Clarke <pc@us.ibm.com>,
kajoljain <kjain@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>,
Sandeep Dasgupta <sdasgup@google.com>,
linux-perf-users@vger.kernel.org, Ian Rogers <irogers@google.com>
Subject: [PATCH v3 0/5] Don't compute events that won't be used in a metric.
Date: Fri, 20 Nov 2020 19:11:14 -0800 [thread overview]
Message-ID: <20201121031119.3554769-1-irogers@google.com> (raw)
For a metric like:
EVENT1 if #smt_on else EVENT2
currently EVENT1 and EVENT2 will be measured and then when the metric
is reported EVENT1 or EVENT2 will be printed depending on the value
from smt_on() during the expr parsing. Computing both events is
unnecessary and can lead to multiplexing as discussed in this thread:
https://lore.kernel.org/lkml/20201110100346.2527031-1-irogers@google.com/
This change modifies expression parsing so that constants are
considered when building the set of ids (events) and only events not
contributing to a constant value are measured.
v3. fixes an assignment in patch 2/5. In patch 5/5 additional comments
are added and useless frees are replaced by asserts. A new peephole
optimization is added for the case CONST IF expr ELSE CONST, where the
the constants are identical, as we don't need to evaluate the IF
condition.
v2. is a rebase.
Ian Rogers (5):
perf metric: Restructure struct expr_parse_ctx.
perf metric: Use NAN for missing event IDs.
perf metric: Rename expr__find_other.
perf metric: Add utilities to work on ids map.
perf metric: Don't compute unused events.
tools/perf/tests/expr.c | 159 +++++++++-----
tools/perf/tests/pmu-events.c | 42 ++--
tools/perf/util/expr.c | 136 ++++++++++--
tools/perf/util/expr.h | 17 +-
tools/perf/util/expr.l | 9 -
tools/perf/util/expr.y | 376 +++++++++++++++++++++++++++-------
tools/perf/util/metricgroup.c | 44 ++--
tools/perf/util/stat-shadow.c | 54 +++--
8 files changed, 623 insertions(+), 214 deletions(-)
--
2.29.2.454.gaff20da3a2-goog
next reply other threads:[~2020-11-21 3:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-21 3:11 Ian Rogers [this message]
2020-11-21 3:11 ` [PATCH v3 1/5] perf metric: Restructure struct expr_parse_ctx Ian Rogers
2020-11-21 3:11 ` [PATCH v3 2/5] perf metric: Use NAN for missing event IDs Ian Rogers
2020-11-21 3:11 ` [PATCH v3 3/5] perf metric: Rename expr__find_other Ian Rogers
2020-11-21 3:11 ` [PATCH v3 4/5] perf metric: Add utilities to work on ids map Ian Rogers
2020-11-21 3:11 ` [PATCH v3 5/5] perf metric: Don't compute unused events Ian Rogers
2020-11-23 5:46 ` Andi Kleen
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