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>,
John Garry <john.garry@huawei.com>,
Kajol Jain <kjain@linux.ibm.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: eranian@google.com, Ian Rogers <irogers@google.com>
Subject: [PATCH v3] perf test: Make metric testing more robust.
Date: Thu, 23 Dec 2021 10:56:22 -0800 [thread overview]
Message-ID: <20211223185622.3435128-1-irogers@google.com> (raw)
When testing metric expressions we fake counter values from 1 going
upward. For some metrics this can yield negative values that are clipped
to zero, and then cause divide by zero failures. Such clipping is
questionable but may be a result of tools automatically generating
metrics. A workaround for this case is to try a second time with counter
values going in the opposite direction.
This case was seen in a metric like:
event1 / max(event2 - event3, 0)
But it may also happen in more sensible metrics like:
event1 / (event2 + event3 - 1 - event4)
v2. Rebase and more detail in commit message.
v3. Is a rebase.
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/tests/pmu-events.c | 32 ++++++++++++++++++++++++++------
1 file changed, 26 insertions(+), 6 deletions(-)
diff --git a/tools/perf/tests/pmu-events.c b/tools/perf/tests/pmu-events.c
index df1c9a3cc05b..b2ddf928d32a 100644
--- a/tools/perf/tests/pmu-events.c
+++ b/tools/perf/tests/pmu-events.c
@@ -962,8 +962,18 @@ static int test__parsing(struct test_suite *test __maybe_unused,
}
if (expr__parse(&result, ctx, pe->metric_expr)) {
- expr_failure("Parse failed", map, pe);
- ret++;
+ /*
+ * Parsing failed, make numbers go from large to
+ * small which can resolve divide by zero
+ * issues.
+ */
+ k = 1024;
+ hashmap__for_each_entry(ctx->ids, cur, bkt)
+ expr__add_id_val(ctx, strdup(cur->key), k--);
+ if (expr__parse(&result, ctx, pe->metric_expr)) {
+ expr_failure("Parse failed", map, pe);
+ ret++;
+ }
}
}
}
@@ -1022,10 +1032,20 @@ static int metric_parse_fake(const char *str)
}
}
- if (expr__parse(&result, ctx, str))
- pr_err("expr__parse failed\n");
- else
- ret = 0;
+ ret = 0;
+ if (expr__parse(&result, ctx, str)) {
+ /*
+ * Parsing failed, make numbers go from large to small which can
+ * resolve divide by zero issues.
+ */
+ i = 1024;
+ hashmap__for_each_entry(ctx->ids, cur, bkt)
+ expr__add_id_val(ctx, strdup(cur->key), i--);
+ if (expr__parse(&result, ctx, str)) {
+ pr_err("expr__parse failed\n");
+ ret = -1;
+ }
+ }
out:
expr__ctx_free(ctx);
--
2.34.1.307.g9b7440fafd-goog
next reply other threads:[~2021-12-23 18:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-23 18:56 Ian Rogers [this message]
2021-12-24 8:49 ` [PATCH v3] perf test: Make metric testing more robust John Garry
2022-02-15 15:10 ` Arnaldo Carvalho de Melo
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