From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 202DA360EC9; Fri, 31 Jul 2026 22:01:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785535308; cv=none; b=l4cpEiDinuJ//6N8w7bYdrMkaJmAXW8WgyREwxi4J9xHIgn4lvWNagk1jQc3O1gacuNJBf1lA6BamtCwOkGTN9jZvVEn+1Pp2jCFL6jh3uTj285Uu+6TgK4cqb/v0oEGoDNW4ddciqQiQpyTVFFr0R4g6VcWHWYySl+gb0APlXY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785535308; c=relaxed/simple; bh=uKYikd2mVQNZ1VGYe342htO7GIUKF6i9NqEBTfAElwI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=rE/iDU2ORyojBWLkS0wxaFdP6ngVd3NwST8FOVr6G6LFb5v5C2WEOgfmrT6wBcC0/acnz8lYGg6FkTvFpNYpgxGh3nXXTxtruPa8ry5PXU2T6K4i6gveylY+43g3mqTJznGMrWaoifP5onZr8NEhViDBJRZnRAS5GwQu89lQ5RE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KyWNfmjt; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KyWNfmjt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DC581F00AC4; Fri, 31 Jul 2026 22:01:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785535307; bh=wsuLrkdoUKeF2en7zAA3Fbfk2jDB3PrDyYbtFD8nnFs=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=KyWNfmjtbX6asvvK/StkZLfwK/OkNt5zi6YxH0hnqRT82ifVR+yB0X1o7wCegcp6Q 5KDJEu2fC0an3Wx68nKi99kE/wka0ay1YFcn54fFckaz8rS+rA3mEQcqlgZYJEvhnE OzIV7dTBmQ0ktYqwX/mKKwk1sdEvCsjap9xBpS+cOpBJP+oOFT6qiynQryRmJyb3Dw QJhhwL/2P/jcntCFLQuBPaPa0IaRmAmJmNrEdz17k4YB+dsPsqA2LnIEbAs+0kizIR CZKwkxjs8KWxRJPrs/eKzFCFgXCufAC3LA8exZougT9xYmCIfu5tXmrnq2MRulOq7l NDXCGwEubseTQ== Date: Fri, 31 Jul 2026 15:01:45 -0700 From: Namhyung Kim To: Aaron Tomlin Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, james.clark@linaro.org, howardchu95@gmail.com, neelx@suse.com, chjohnst@mail.com, sean@ashe.io, steve@abita.co, rishil1999@outlook.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 2/3] perf sched latency: Auto-scale latency and runtime display units Message-ID: References: <20260730185416.97166-1-atomlin@atomlin.com> <20260730185416.97166-3-atomlin@atomlin.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260730185416.97166-3-atomlin@atomlin.com> On Thu, Jul 30, 2026 at 02:54:15PM -0400, Aaron Tomlin wrote: > Currently, 'perf sched latency' displays task runtime and delay values > exclusively in milliseconds (ms). This can be hard to read when > latencies are very small (in the microsecond or nanosecond range) or > unusually large (seconds). > > Introduce auto-scaling for latency and runtime display columns. Values > are dynamically scaled and output with the most appropriate unit: > nanoseconds (ns), microseconds (us), milliseconds (ms), or seconds (s). > > Additionally, rename column headers from "Runtime ms", "Avg delay ms", > and "Max delay ms" to "Runtime", "Avg delay", and "Max delay" > respectively, adjust spacing to maintain column alignment and stripe > redundant prefix strings from each row's format string to produce a > clean, tabular output. It'd be nice if you could include example output when you touched user- visible area. Comparing before and after would be great. Thanks, Namhyung > > Signed-off-by: Aaron Tomlin > --- > tools/perf/builtin-sched.c | 42 +++++++++++++++++++++++++++----------- > 1 file changed, 30 insertions(+), 12 deletions(-) > > diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c > index 0abf9f1f3c2e..bfbedd12b346 100644 > --- a/tools/perf/builtin-sched.c > +++ b/tools/perf/builtin-sched.c > @@ -246,6 +246,17 @@ struct perf_sched { > struct perf_data *data; > }; > > +static int scnprintf_latency_unit(char *buf, size_t size, u64 nsecs) > +{ > + if (nsecs < 1000) > + return scnprintf(buf, size, "%6" PRIu64 " ns", nsecs); > + if (nsecs < NSEC_PER_MSEC) > + return scnprintf(buf, size, "%6.3f us", (double)nsecs / NSEC_PER_USEC); > + if (nsecs < NSEC_PER_SEC) > + return scnprintf(buf, size, "%6.3f ms", (double)nsecs / NSEC_PER_MSEC); > + return scnprintf(buf, size, "%6.3f s ", (double)nsecs / NSEC_PER_SEC); > +} > + > /* per thread run time data */ > struct thread_runtime { > u64 last_time; /* time of previous sched in/out event */ > @@ -1405,6 +1416,8 @@ static void output_lat_thread(struct perf_sched *sched, struct work_atoms *work_ > int i; > int ret; > u64 avg; > + char runtime_lat[32]; > + char avg_lat[32], max_lat[32]; > char max_lat_start[32], max_lat_end[32]; > > if (!work_list->nb_atoms) > @@ -1430,14 +1443,17 @@ static void output_lat_thread(struct perf_sched *sched, struct work_atoms *work_ > printf(" "); > > avg = work_list->total_lat / work_list->nb_atoms; > + scnprintf_latency_unit(runtime_lat, sizeof(runtime_lat), work_list->total_runtime); > + scnprintf_latency_unit(avg_lat, sizeof(avg_lat), avg); > + scnprintf_latency_unit(max_lat, sizeof(max_lat), work_list->max_lat); > timestamp__scnprintf_usec(work_list->max_lat_start, max_lat_start, sizeof(max_lat_start)); > timestamp__scnprintf_usec(work_list->max_lat_end, max_lat_end, sizeof(max_lat_end)); > > - printf("|%11.3f ms |%9" PRIu64 " | avg:%8.3f ms | max:%8.3f ms | max start: %12s s | max end: %12s s\n", > - (double)work_list->total_runtime / NSEC_PER_MSEC, > - work_list->nb_atoms, (double)avg / NSEC_PER_MSEC, > - (double)work_list->max_lat / NSEC_PER_MSEC, > - max_lat_start, max_lat_end); > + printf(" |%15s |%9" PRIu64 " |%16s |%16s |%20s s |%20s s |\n", > + runtime_lat, > + work_list->nb_atoms, avg_lat, max_lat, > + max_lat_start, max_lat_end); > + > } > > static int pid_cmp(struct work_atoms *l, struct work_atoms *r) > @@ -3616,6 +3632,7 @@ static int perf_sched__lat(struct perf_sched *sched) > { > int rc = -1; > struct rb_node *next; > + char total_runtime_str[32]; > > setup_pager(); > > @@ -3628,9 +3645,9 @@ static int perf_sched__lat(struct perf_sched *sched) > perf_sched__merge_lat(sched); > perf_sched__sort_lat(sched); > > - printf("\n -------------------------------------------------------------------------------------------------------------------------------------------\n"); > - printf(" Task | Runtime ms | Count | Avg delay ms | Max delay ms | Max delay start | Max delay end |\n"); > - printf(" -------------------------------------------------------------------------------------------------------------------------------------------\n"); > + printf("\n -----------------------------------------------------------------------------------------------------------------------------------------\n"); > + printf(" Task | Runtime | Count | Avg delay | Max delay | Max delay start | Max delay end |\n"); > + printf(" -----------------------------------------------------------------------------------------------------------------------------------------\n"); > > next = rb_first_cached(&sched->sorted_atom_root); > > @@ -3642,11 +3659,12 @@ static int perf_sched__lat(struct perf_sched *sched) > next = rb_next(next); > } > > - printf(" -----------------------------------------------------------------------------------------------------------------\n"); > - printf(" TOTAL: |%11.3f ms |%9" PRIu64 " |\n", > - (double)sched->all_runtime / NSEC_PER_MSEC, sched->all_count); > + printf(" -----------------------------------------------------------------------------------------------------------------------------------------\n"); > + scnprintf_latency_unit(total_runtime_str, sizeof(total_runtime_str), sched->all_runtime); > + printf(" TOTAL: |%15s |%9" PRIu64 " |\n", > + total_runtime_str, sched->all_count); > > - printf(" ---------------------------------------------------\n"); > + printf(" -----------------------------------------------------\n"); > > print_bad_events(sched); > printf("\n"); > -- > 2.55.0 >