1RTLA-OSNOISE-HIST(1)                                      RTLA-OSNOISE-HIST(1)
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NAME

6       rtla-osnoise-hist - Display a histogram of the osnoise tracer samples
7

SYNOPSIS

9       rtla osnoise hist [OPTIONS]
10

DESCRIPTION

12       The  rtla  osnoise tool is an interface for the osnoise tracer. The os‐
13       noise tracer dispatches a kernel thread per-cpu. These threads read the
14       time  in  a  loop while with preemption, softirq and IRQs enabled, thus
15       allowing all the sources of operating system noise  during  its  execu‐
16       tion.  The osnoise's tracer threads take note of the delta between each
17       time read, along with an interference counter of all sources of  inter‐
18       ference.  At the end of each period, the osnoise tracer displays a sum‐
19       mary of the results.
20
21       The rtla osnoise hist tool collects all osnoise:sample_threshold occur‐
22       rence  in  a  histogram, displaying the results in a user-friendly way.
23       The tool also allows many configurations of the osnoise tracer and  the
24       collection of the tracer output.
25

OPTIONS

27       -a, --auto us
28          Set  the automatic trace mode. This mode sets some commonly used op‐
29          tions while debugging the system. It is equivalent to use -s us -T 1
30          -t.
31
32       -p, --period us
33          Set the osnoise tracer period in microseconds.
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35       -r, --runtime us
36          Set the osnoise tracer runtime in microseconds.
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38       -s, --stop us
39          Stop the trace if a single sample is higher than the argument in mi‐
40          croseconds.  If -T is set, it will also save the trace to  the  out‐
41          put.
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43       -S, --stop-total us
44          Stop  the  trace  if the total sample is higher than the argument in
45          microseconds.  If -T is set, it will also save the trace to the out‐
46          put.
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48       -T, --threshold us
49          Specify  the  minimum  delta between two time reads to be considered
50          noise.  The default threshold is 5 us.
51
52       -b, --bucket-size N
53          Set the histogram bucket size (default 1).
54
55       -E, --entries N
56          Set the number of entries of the histogram (default 256).
57
58       --no-header
59          Do not print header.
60
61       --no-summary
62          Do not print summary.
63
64       --no-index
65          Do not print index.
66
67       --with-zeros
68          Print zero only entries.
69
70       -c, --cpus cpu-list
71          Set the osnoise tracer to run the sample threads in the cpu-list.
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73       -d, --duration time[s|m|h|d]
74          Set the duration of the session.
75
76       -D, --debug
77          Print debug info.
78
79       -t, --trace[=file]
80          Save the stopped trace to [file|osnoise_trace.txt].
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82       -e, --event sys:event
83          Enable an event in the trace (-t) session. The  argument  can  be  a
84          specific event, e.g., -e sched:sched_switch, or all events of a sys‐
85          tem group, e.g., -e sched. Multiple -e are allowed. It is  only  ac‐
86          tive when -t or -a are set.
87
88       --filter <filter>
89          Filter  the  previous  -e sys:event event with <filter>. For further
90          information        about         event         filtering         see
91          https://www.kernel.org/doc/html/latest/trace/events.html#event-filtering.
92
93       --trigger <trigger>
94              Enable a trace event trigger to the previous -e  sys:event.   If
95              the hist: trigger is activated, the output histogram will be au‐
96              tomatically saved to a file  named  system_event_hist.txt.   For
97              example, the command:
98
99              rtla   <command>   <mode>   -t   -e   osnoise:irq_noise  --trig‐
100              ger="hist:key=desc,duration/1000:sort=desc,dura‐
101              tion/1000:vals=hitcount"
102
103              Will  automatically save the content of the histogram associated
104              to osnoise:irq_noise event in osnoise_irq_noise_hist.txt.
105
106              For   further    information    about    event    trigger    see
107              https://www.kernel.org/doc/html/latest/trace/events.html#event-triggers.
108
109       -P, --priority o:prio|r:prio|f:prio|d:runtime:period
110          Set scheduling parameters to the osnoise tracer threads, the  format
111          to set the priority are:
112
113o:prio - use SCHED_OTHER with prio;
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115r:prio - use SCHED_RR with prio;
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117f:prio - use SCHED_FIFO with prio;
118
119d:runtime[us|ms|s]:period[us|ms|s]  - use SCHED_DEADLINE with run‐
120            time and period in nanoseconds.
121
122       -h, --help
123          Print help menu.
124

EXAMPLE

126       In the example below, osnoise  tracer  threads  are  set  to  run  with
127       real-time  priority  FIFO:1, on CPUs 0-11, for 900ms at each period (1s
128       by default). The reason for reducing the runtime is to  avoid  starving
129       the  rtla  tool. The tool is also set to run for one minute. The output
130       histogram is set to group outputs in buckets of 10us and 25 entries:
131
132          [root@f34 ~/]# rtla osnoise hist -P F:1 -c 0-11 -r 900000 -d 1M -b 10 -E 25
133          # RTLA osnoise histogram
134          # Time unit is microseconds (us)
135          # Duration:   0 00:01:00
136          Index   CPU-000   CPU-001   CPU-002   CPU-003   CPU-004   CPU-005   CPU-006   CPU-007   CPU-008   CPU-009   CPU-010   CPU-011
137          0         42982     46287     51779     53740     52024     44817     49898     36500     50408     50128     49523     52377
138          10        12224      8356      2912       878      2667     10155      4573     18894      4214      4836      5708      2413
139          20            8         5        12         2        13        24        20        41        29        53        39        39
140          30            1         1         0         0        10         3         6        19        15        31        30        38
141          40            0         0         0         0         0         4         2         7         2         3         8        11
142          50            0         0         0         0         0         0         0         0         0         1         1         2
143          over:         0         0         0         0         0         0         0         0         0         0         0         0
144          count:    55215     54649     54703     54620     54714     55003     54499     55461     54668     55052     55309     54880
145          min:          0         0         0         0         0         0         0         0         0         0         0         0
146          avg:          0         0         0         0         0         0         0         0         0         0         0         0
147          max:         30        30        20        20        30        40        40        40        40        50        50        50
148

SEE ALSO

150       rtla-osnoise(1), rtla-osnoise-top(1)
151
152       osnoise              tracer              documentation:              <‐
153       https://www.kernel.org/doc/html/latest/trace/osnoise-tracer.html>
154

AUTHOR

156       Written by Daniel Bristot de Oliveira <bristot@kernel.org>
157

REPORTING BUGS

159       Report     bugs     to     <linux-kernel@vger.kernel.org>     and    <‐
160       linux-trace-devel@vger.kernel.org>
161

LICENSE

163       rtla is Free Software licensed under the GNU GPLv2
164

COPYING

166       Copyright (C) 2021 Red Hat, Inc. Free use of this software  is  granted
167       under the terms of the GNU Public License (GPL).
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172                                                          RTLA-OSNOISE-HIST(1)
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