From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3EEC1C433F5 for ; Fri, 24 Dec 2021 08:49:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237953AbhLXItr (ORCPT ); Fri, 24 Dec 2021 03:49:47 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:4322 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343657AbhLXItl (ORCPT ); Fri, 24 Dec 2021 03:49:41 -0500 Received: from fraeml708-chm.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4JL0xV4zSPz67cpv; Fri, 24 Dec 2021 16:45:02 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml708-chm.china.huawei.com (10.206.15.36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Fri, 24 Dec 2021 09:49:38 +0100 Received: from [10.195.32.200] (10.195.32.200) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Fri, 24 Dec 2021 08:49:37 +0000 Subject: Re: [PATCH v3] perf test: Make metric testing more robust. To: Ian Rogers , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , "Namhyung Kim" , Kajol Jain , , CC: References: <20211223185622.3435128-1-irogers@google.com> From: John Garry Message-ID: Date: Fri, 24 Dec 2021 08:49:35 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <20211223185622.3435128-1-irogers@google.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.195.32.200] X-ClientProxiedBy: lhreml729-chm.china.huawei.com (10.201.108.80) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Reviewed-by: John Garry > --- > 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); >