From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 18C461C08 for ; Wed, 28 Dec 2022 16:33:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69E5EC433D2; Wed, 28 Dec 2022 16:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672245230; bh=+HuI+g0asqjES+zSD1OTyZ0hRb5dGmMVacV0sRnOiRE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P9yWgK2gBGvNF8Kn7hXhbjJzU+MHmh89jN6bk24CgmTF/vKXnfQC12WO7CEtxWZAY YVQBigtBOMJNHTZx++7+SA2x9gvxhWLYuf86teDEQKNikdka7xmmbBwvOoAZz1h2AF oDP3i4M+v/oCpRQ6JlHTzrWN0sxiYVHX/FwPSHWc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kevin Nomura , Namhyung Kim , Thomas Richter , Adrian Hunter , Ian Rogers , Ingo Molnar , Jiri Olsa , Peter Zijlstra , Sumanth Korikkar , Arnaldo Carvalho de Melo , Sasha Levin Subject: [PATCH 6.1 0788/1146] perf stat: Do not delay the workload with --delay Date: Wed, 28 Dec 2022 15:38:47 +0100 Message-Id: <20221228144351.550442048@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20221228144330.180012208@linuxfoundation.org> References: <20221228144330.180012208@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Namhyung Kim [ Upstream commit c587e77e100fa40eb6af10e00497c67acf493f33 ] The -D/--delay option is to delay the measure after the program starts. But the current code goes to sleep before starting the program so the program is delayed too. This is not the intention, let's fix it. Before: $ time sudo ./perf stat -a -e cycles -D 3000 sleep 4 Events disabled Events enabled Performance counter stats for 'system wide': 4,326,949,337 cycles 4.007494118 seconds time elapsed real 0m7.474s user 0m0.356s sys 0m0.120s It ran the workload for 4 seconds and gave the 3 second delay. So it should skip the first 3 second and measure the last 1 second only. But as you can see, it delays 3 seconds and ran the workload after that for 4 seconds. So the total time (real) was 7 seconds. After: $ time sudo ./perf stat -a -e cycles -D 3000 sleep 4 Events disabled Events enabled Performance counter stats for 'system wide': 1,063,551,013 cycles 1.002769510 seconds time elapsed real 0m4.484s user 0m0.385s sys 0m0.086s The bug was introduced when it changed enablement of system-wide events with a command line workload. But it should've considered the initial delay case. The code was reworked since then (in bb8bc52e7578) so I'm afraid it won't be applied cleanly. Fixes: d0a0a511493d2695 ("perf stat: Fix forked applications enablement of counters") Reported-by: Kevin Nomura Signed-off-by: Namhyung Kim Tested-by: Thomas Richter Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Peter Zijlstra Cc: Sumanth Korikkar Link: https://lore.kernel.org/r/20221212230820.901382-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin --- tools/perf/builtin-stat.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-) diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index 265b05157972..d726c3d3d83c 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -528,26 +528,14 @@ static int enable_counters(void) return err; } - if (stat_config.initial_delay < 0) { - pr_info(EVLIST_DISABLED_MSG); - return 0; - } - - if (stat_config.initial_delay > 0) { - pr_info(EVLIST_DISABLED_MSG); - usleep(stat_config.initial_delay * USEC_PER_MSEC); - } - /* * We need to enable counters only if: * - we don't have tracee (attaching to task or cpu) * - we have initial delay configured */ - if (!target__none(&target) || stat_config.initial_delay) { + if (!target__none(&target)) { if (!all_counters_use_bpf) evlist__enable(evsel_list); - if (stat_config.initial_delay > 0) - pr_info(EVLIST_ENABLED_MSG); } return 0; } @@ -918,14 +906,27 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx) return err; } - err = enable_counters(); - if (err) - return -1; + if (stat_config.initial_delay) { + pr_info(EVLIST_DISABLED_MSG); + } else { + err = enable_counters(); + if (err) + return -1; + } /* Exec the command, if any */ if (forks) evlist__start_workload(evsel_list); + if (stat_config.initial_delay > 0) { + usleep(stat_config.initial_delay * USEC_PER_MSEC); + err = enable_counters(); + if (err) + return -1; + + pr_info(EVLIST_ENABLED_MSG); + } + t0 = rdclock(); clock_gettime(CLOCK_MONOTONIC, &ref_time); -- 2.35.1