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 D8855C46CA3 for ; Tue, 5 Dec 2023 16:28:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232141AbjLEQ2m (ORCPT ); Tue, 5 Dec 2023 11:28:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38748 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346293AbjLEPZs (ORCPT ); Tue, 5 Dec 2023 10:25:48 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89C229B for ; Tue, 5 Dec 2023 07:25:54 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9896EC433C9; Tue, 5 Dec 2023 15:25:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701789954; bh=jGbR98Oq7+B1xcOqIwhdrfRm9TOrFrBuvflXUQyUyQw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ipFqaA62uI4kOw0gXHgoFGKMBznOLI1pIAxiYjWqNP6oK5LvRB2V1o/kVsVGoy2M2 Mog3RVBn40qGnjn+/8PsCuqetBQvplxvn4AWU34QgMifHHgMp8V7N9/MypAHDj9A+H 1PgTycir+nZf7ju4ys7jMPjlwwT9ZR7DFRzsToN6E5Roczywtgcqw+awrY8wJmfp1w Eg6QFRzwEp93ONJtuxIGy4pv0W9kKwHdccN4Hgs6F4XIA7yWxjfn0PQjKraGeHHanK iqSwwW6tukzW6uQyEvBkUNXvYWD3MaqSmp52M9YU0O0kz2OigZ5LKZAvSUt+FA+nBS npiWRxXmDLqow== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id E1D4840094; Tue, 5 Dec 2023 12:25:50 -0300 (-03) Date: Tue, 5 Dec 2023 12:25:50 -0300 From: Arnaldo Carvalho de Melo To: Athira Rajeev Cc: Ian Rogers , Namhyung Kim , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Kan Liang , Yang Jihong , Leo Yan , Sandipan Das , Ravi Bangoria , linux-perf-users , LKML , Ajay Kaher , Alexey Makhalov Subject: Re: [RFC PATCH v2] perf evsel: Fallback to task-clock when not system wide Message-ID: References: <20231121000420.368075-1-irogers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Url: http://acmel.wordpress.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Tue, Dec 05, 2023 at 04:51:01PM +0530, Athira Rajeev escreveu: > > > > On 21-Nov-2023, at 5:34 AM, Ian Rogers wrote: > > > > When the cycles event isn't available evsel will fallback to the > > cpu-clock software event. task-clock is similar to cpu-clock but only > > runs when the process is running. Falling back to cpu-clock when not > > system wide leads to confusion, by falling back to task-clock it is > > hoped the confusion is less. > > > > Pass the target to determine if task-clock is more appropriate. Update > > a nearby comment and debug string for the change. > > > > --- > > v2. Use target__has_cpu as suggested by Namhyung. > > https://lpc.events/event/17/contributions/1556/ > > > > Signed-off-by: Ian Rogers > > --- > > tools/perf/builtin-record.c | 2 +- > > tools/perf/builtin-stat.c | 2 +- > > tools/perf/builtin-top.c | 2 +- > > tools/perf/util/evsel.c | 18 ++++++++++-------- > > tools/perf/util/evsel.h | 3 ++- > > 5 files changed, 15 insertions(+), 12 deletions(-) > > > > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > > index 8ec818568662..d8bb59511fdd 100644 > > --- a/tools/perf/builtin-record.c > > +++ b/tools/perf/builtin-record.c > > @@ -1350,7 +1350,7 @@ static int record__open(struct record *rec) > > evlist__for_each_entry(evlist, pos) { > > try_again: > > if (evsel__open(pos, pos->core.cpus, pos->core.threads) < 0) { > > - if (evsel__fallback(pos, errno, msg, sizeof(msg))) { > > + if (evsel__fallback(pos, &opts->target, errno, msg, sizeof(msg))) { > > Hi Ian > > Tested this with perf record and I could find the code fallback to using task-clock > > ./perf record -v ls > Warning: > The cycles event is not supported, trying to fall back to task-clock Ok, so I'll take that as a Tested-by: you, ok? The "perf stat" part can be addressed in a follow up patch, when that error handling is researched to remember why we have that ->supported, ->errored thing. - Arnaldo > But in case of “perf stat”, in my environment, found that the code path won't invoke “evsel__fallback”. > > Snippet for builtin-stat.c > if (errno == EINVAL || errno == ENOSYS || > errno == ENOENT || errno == EOPNOTSUPP || > errno == ENXIO) { > if (verbose > 0) > ui__warning("%s event is not supported by the kernel.\n", > evsel__name(counter)); > counter->supported = false; > /* > * errored is a sticky flag that means one of the counter's > * cpu event had a problem and needs to be reexamined. > */ > counter->errored = true; > > if ((evsel__leader(counter) != counter) || > !(counter->core.leader->nr_members > 1)) > return COUNTER_SKIP; > } else if (evsel__fallback(counter, &target, errno, msg, sizeof(msg))) { > if (verbose > 0) > ui__warning("%s\n", msg); > return COUNTER_RETRY; > > So if the perf_event_open returns ENOENT, we won’t do a fallback in builtin-stat.c > Should we address cycles differently here ? Any comments ? > > Thanks > Athira > > > > if (verbose > 0) > > ui__warning("%s\n", msg); > > goto try_again; > > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c > > index a3af805a1d57..d8e5d6f7a87a 100644 > > --- a/tools/perf/builtin-stat.c > > +++ b/tools/perf/builtin-stat.c > > @@ -653,7 +653,7 @@ static enum counter_recovery stat_handle_error(struct evsel *counter) > > if ((evsel__leader(counter) != counter) || > > !(counter->core.leader->nr_members > 1)) > > return COUNTER_SKIP; > > - } else if (evsel__fallback(counter, errno, msg, sizeof(msg))) { > > + } else if (evsel__fallback(counter, &target, errno, msg, sizeof(msg))) { > > if (verbose > 0) > > ui__warning("%s\n", msg); > > return COUNTER_RETRY; > > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c > > index ea8c7eca5eee..1e42bd1c7d5a 100644 > > --- a/tools/perf/builtin-top.c > > +++ b/tools/perf/builtin-top.c > > @@ -1044,7 +1044,7 @@ static int perf_top__start_counters(struct perf_top *top) > > perf_top_overwrite_fallback(top, counter)) > > goto try_again; > > > > - if (evsel__fallback(counter, errno, msg, sizeof(msg))) { > > + if (evsel__fallback(counter, &opts->target, errno, msg, sizeof(msg))) { > > if (verbose > 0) > > ui__warning("%s\n", msg); > > goto try_again; > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > > index a5da74e3a517..532f34d9fcb5 100644 > > --- a/tools/perf/util/evsel.c > > +++ b/tools/perf/util/evsel.c > > @@ -2853,7 +2853,8 @@ u64 evsel__intval_common(struct evsel *evsel, struct perf_sample *sample, const > > > > #endif > > > > -bool evsel__fallback(struct evsel *evsel, int err, char *msg, size_t msgsize) > > +bool evsel__fallback(struct evsel *evsel, struct target *target, int err, > > + char *msg, size_t msgsize) > > { > > int paranoid; > > > > @@ -2861,18 +2862,19 @@ bool evsel__fallback(struct evsel *evsel, int err, char *msg, size_t msgsize) > > evsel->core.attr.type == PERF_TYPE_HARDWARE && > > evsel->core.attr.config == PERF_COUNT_HW_CPU_CYCLES) { > > /* > > - * If it's cycles then fall back to hrtimer based > > - * cpu-clock-tick sw counter, which is always available even if > > - * no PMU support. > > + * If it's cycles then fall back to hrtimer based cpu-clock sw > > + * counter, which is always available even if no PMU support. > > * > > * PPC returns ENXIO until 2.6.37 (behavior changed with commit > > * b0a873e). > > */ > > - scnprintf(msg, msgsize, "%s", > > -"The cycles event is not supported, trying to fall back to cpu-clock-ticks"); > > - > > evsel->core.attr.type = PERF_TYPE_SOFTWARE; > > - evsel->core.attr.config = PERF_COUNT_SW_CPU_CLOCK; > > + evsel->core.attr.config = target__has_cpu(target) > > + ? PERF_COUNT_SW_CPU_CLOCK > > + : PERF_COUNT_SW_TASK_CLOCK; > > + scnprintf(msg, msgsize, > > + "The cycles event is not supported, trying to fall back to %s", > > + target__has_cpu(target) ? "cpu-clock" : "task-clock"); > > > > zfree(&evsel->name); > > return true; > > diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h > > index f19ac9f027ef..efbb6e848287 100644 > > --- a/tools/perf/util/evsel.h > > +++ b/tools/perf/util/evsel.h > > @@ -460,7 +460,8 @@ static inline bool evsel__is_clock(const struct evsel *evsel) > > evsel__match(evsel, SOFTWARE, SW_TASK_CLOCK); > > } > > > > -bool evsel__fallback(struct evsel *evsel, int err, char *msg, size_t msgsize); > > +bool evsel__fallback(struct evsel *evsel, struct target *target, int err, > > + char *msg, size_t msgsize); > > int evsel__open_strerror(struct evsel *evsel, struct target *target, > > int err, char *msg, size_t size); > > > > -- > > 2.43.0.rc1.413.gea7ed67945-goog > > > -- - Arnaldo