mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-10-01 14:44:12 +00:00
Code Issues Releases Wiki Activity

perf test: Make metric testing more robust

Browse source 
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)

Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20211223185622.3435128-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers 2021-12-23 10:56:22 -08:00 committed by Arnaldo Carvalho de Melo
parent aca8af3c2e
commit 87a73bdc42
1 changed files with 26 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

32
tools/perf/tests/pmu-events.c
View file

@ -994,8 +994,18 @@ 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++;
}
}
}
}
@ -1054,10 +1064,20 @@ 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);