lkml.org 
[lkml]   [2021]   [Dec]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v3] perf test: Make metric testing more robust.
From
Date
On 23/12/2021 18:56, Ian Rogers wrote:
> 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.

Incorrect location for this info

>
> Signed-off-by: Ian Rogers <irogers@google.com>

Reviewed-by: John Garry <john.garry@huawei.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

can or may?

> + * 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);
>

\
 
 \ /
  Last update: 2021-12-24 09:50    [W:0.046 / U:0.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site