Man page for rtla timerlat hist mode. Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Tom Zanussi <zanussi@xxxxxxxxxx> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Juri Lelli <juri.lelli@xxxxxxxxxx> Cc: Clark Williams <williams@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx> Cc: linux-rt-users@xxxxxxxxxxxxxxx Cc: linux-trace-devel@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx> --- .../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@alien ~]# 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@xxxxxxxxxx> + +REPORTING BUGS +-------------- +Report bugs to <lkml@xxxxxxxxxxxxxxx> + +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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