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Message-Id: <8c32748235fc2d77070e13baf0cebce5e4b4e1a9.1631889858.git.bristot@kernel.org>
Date: Fri, 17 Sep 2021 17:44:02 +0200
From: Daniel Bristot de Oliveira <bristot@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Jonathan Corbet <corbet@....net>, Kate Carcia <kcarcia@...hat.com>,
Daniel Bristot de Oliveira <bristot@...nel.org>,
Ingo Molnar <mingo@...hat.com>,
Tom Zanussi <zanussi@...nel.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Juri Lelli <juri.lelli@...hat.com>,
Clark Williams <williams@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
linux-rt-users@...r.kernel.org, linux-trace-devel@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [RFC 19/19] rtla: Add rtla timerlat hist documentation
Man page for rtla timerlat hist mode.
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Tom Zanussi <zanussi@...nel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Clark Williams <williams@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Daniel Bristot de Oliveira <bristot@...nel.org>
Cc: linux-rt-users@...r.kernel.org
Cc: linux-trace-devel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@...nel.org>
---
.../rtla/Documentation/rtla-timerlat-hist.txt | 162 ++++++++++++++++++
1 file changed, 162 insertions(+)
create mode 100644 tools/tracing/rtla/Documentation/rtla-timerlat-hist.txt
diff --git a/tools/tracing/rtla/Documentation/rtla-timerlat-hist.txt b/tools/tracing/rtla/Documentation/rtla-timerlat-hist.txt
new file mode 100644
index 000000000000..fbbc981aa82d
--- /dev/null
+++ b/tools/tracing/rtla/Documentation/rtla-timerlat-hist.txt
@@ -0,0 +1,162 @@
+rtla-timerlat-hist(1)
+=====================
+
+NAME
+----
+rtla-timerlat-hist - Histograms of the operating system timer latency
+
+SYNOPSIS
+--------
+*rtla timerlat hist* ['OPTIONS'] ...
+
+DESCRIPTION
+-----------
+The rtla-hist-hist(1) mode displays a histogram of each tracer event occurrence.
+
+The rtla-timerlat(1) tool is an interface for the timerlat tracer. The
+timerlat tracer dispatches a kernel thread per-cpu. These threads set a
+periodic timer to wake themselves up and go back to sleep. After the wakeup,
+they collect and generate useful information for the debugging of operating
+system timer latency.
+
+The timerlat tracer outputs information in two ways. It periodically prints
+the timer latency at the timer 'IRQ' handler and the 'Thread' handler. It
+also provides information for each noise via the osnoise tracepoints. This
+tool uses the periodic information, and the osnoise tracepoints are enabled
+when using the -T option.
+
+OPTIONS
+-------
+*-h*, *--help*::
+Print help menu.
+*-p*, *--period* 'us'::
+Set the timerlat tracer period in microseconds.
+*-i*, *--irq* 'us'::
+Stop trace if the irq latency is higher than the argument in us.
+*-T*, *--thread* 'us'::
+Stop trace if the thread latency is higher than the argument in us.
+*-s*, *--stack* 'us'::
+Save the stack trace at the IRQ if a thread latency is higher than the
+argument in us.
+*-c*, *--cpus* 'cpu-list'::
+Set the timerlat tracer to run the sample threads in the cpu-list.
+*-d*, *--duration* 'time[s|m|h|d]'::
+Set the duration of the session.
+*-T*, *--trace*['=file']::
+Save the stopped trace to ['file|timerlat_trace.txt'].
+*-P*, *--priority* 'o:prio|r:prio|f:prio|d:runtime:period'::
+Set scheduling parameters to the timerlat tracer threads, the format to
+set the priority are:
+ - 'o:prio' - use SCHED_OTHER with 'prio';
+ - 'r:prio' - use SCHED_RR with 'prio';
+ - 'f:prio' - use SCHED_FIFO with 'prio';
+ - 'd:runtime[us|ms|s]:period[us|ms|s]' - use SCHED_DEADLINE with 'runtime' and
+'period' in nanoseconds.
+
+*-b*, *--bucket-size* 'N'::
+Set the histogram bucket size (default 1).
+*-e*, *--entries* 'N'::
+Set the number of entries of the histogram (default 256).
+*--no-irq*::
+Ignore IRQ latencies.
+*--no-thread*::
+Ignore thread latencies.
+*--no-header*::
+So not print header.
+*--no-summary*::
+Do not print summary.
+*--no-index*::
+So not print index.
+*--skip-zeros*::
+Skip zero only entries.
+
+EXAMPLE
+-------
+In the example below, *rtla timerlat hist* is set to run for '10' minutes,
+in the cpus '0-4', 'skipping zero' only lines. Moreover, *rtla timerlat
+hist* will change the priority of the timelat threads to run under
+'SCHED_DEADLINE' priority, with a '10 us' runtime every '1 ms' period. The
+'1ms' period is also passed to the timerlat tracer.
+
+------------------------------------------
+[root@...en ~]# timerlat hist -d 10m -c 0-4 --skip-zeros -P d:100us:1ms -p 1ms
+# RTLA timerlat histogram
+# Time unit is microseconds (us)
+# Duration: 0 00:10:00
+Index IRQ-000 Thr-000 IRQ-001 Thr-001 IRQ-002 Thr-002 IRQ-003 Thr-003 IRQ-004 Thr-004
+0 276489 0 206089 0 466018 0 481102 0 205546 0
+1 318327 35487 388149 30024 94531 48382 83082 71078 388026 55730
+2 3282 122584 4019 126527 28231 109012 23311 89309 4568 98739
+3 940 11815 837 9863 6209 16227 6895 17196 910 9780
+4 444 17287 424 11574 2097 38443 2169 36736 462 13476
+5 206 43291 255 25581 1223 101908 1304 101137 236 28913
+6 132 101501 96 64584 635 213774 757 215471 99 73453
+7 74 169347 65 124758 350 57466 441 53639 69 148573
+8 53 85183 31 156751 229 9052 306 9026 39 139907
+9 22 10387 12 42762 161 2554 225 2689 19 26192
+10 13 1898 8 5770 114 1247 128 1405 13 3772
+11 9 560 9 924 71 686 76 765 8 713
+12 4 256 2 360 50 411 64 474 3 278
+13 2 167 2 172 43 256 53 350 4 180
+14 1 88 1 116 15 198 42 223 0 115
+15 2 63 3 94 11 139 20 150 0 58
+16 2 37 0 56 5 78 10 102 0 39
+17 0 18 0 28 4 57 8 80 0 15
+18 0 8 0 17 2 50 6 56 0 12
+19 0 9 0 5 0 19 0 48 0 18
+20 0 4 0 8 0 11 2 27 0 4
+21 0 2 0 3 1 9 1 18 0 6
+22 0 1 0 3 1 7 0 3 0 5
+23 0 2 0 4 0 2 0 7 0 2
+24 0 2 0 2 1 3 0 3 0 5
+25 0 0 0 1 0 1 0 1 0 3
+26 0 1 0 0 0 2 0 2 0 0
+27 0 0 0 3 0 1 0 0 0 1
+28 0 0 0 3 0 0 0 1 0 0
+29 0 0 0 2 0 2 0 1 0 3
+30 0 1 0 0 0 0 0 0 0 0
+31 0 1 0 0 0 0 0 2 0 2
+32 0 0 0 1 0 2 0 0 0 0
+33 0 0 0 2 0 0 0 0 0 1
+34 0 0 0 0 0 0 0 0 0 2
+35 0 1 0 1 0 0 0 0 0 1
+36 0 1 0 0 0 1 0 1 0 0
+37 0 0 0 1 0 0 0 0 0 0
+40 0 0 0 0 0 1 0 1 0 0
+41 0 0 0 0 0 0 0 0 0 1
+42 0 0 0 0 0 0 0 0 0 1
+44 0 0 0 0 0 1 0 0 0 0
+46 0 0 0 0 0 0 0 1 0 0
+47 0 0 0 0 0 0 0 0 0 1
+50 0 0 0 0 0 0 0 0 0 1
+54 0 0 0 1 0 0 0 0 0 0
+58 0 0 0 1 0 0 0 0 0 0
+over: 0 0 0 0 0 0 0 0 0 0
+count: 600002 600002 600002 600002 600002 600002 600002 600002 600002 600002
+min: 0 1 0 1 0 1 0 1 0 1
+avg: 0 5 0 5 0 4 0 4 0 5
+max: 16 36 15 58 24 44 21 46 13 50
+------------------------------------------
+
+SEE ALSO
+--------
+_rtla-timerlat(1)_, _rtla-timerlat-top(1)_
+
+Timerlat tracer documentation: <https://www.kernel.org/doc/html/latest/trace/timerlat-tracer.html>
+
+AUTHOR
+------
+Written by Daniel Bristot de Oliveira <bristot@...nel.org>
+
+REPORTING BUGS
+--------------
+Report bugs to <lkml@...r.kernel.org>
+
+LICENSE
+-------
+rtla is Free Software licensed under the GNU GPLv2
+
+COPYING
+-------
+Copyright \(C) 2021 Red Hat, Inc. Free use of this software is granted under
+the terms of the GNU Public License (GPL).
--
2.31.1
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