55 lines
1.9 KiB
Plaintext
55 lines
1.9 KiB
Plaintext
Demonstrations of runqslower, the Linux BPF CO-RE version.
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runqslower shows high latency scheduling times between tasks being
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ready to run and them running on CPU after that. For example:
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# runqslower
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Tracing run queue latency higher than 10000 us.
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TIME COMM TID LAT(us)
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04:16:32 cc1 12924 12739
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04:16:32 sh 13640 12118
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04:16:32 make 13639 12730
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04:16:32 bash 13655 12047
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04:16:32 bash 13657 12744
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04:16:32 bash 13656 12880
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04:16:32 sh 13660 10846
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04:16:32 gcc 13663 12681
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04:16:32 make 13668 10814
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04:16:32 make 13670 12988
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04:16:32 gcc 13677 11770
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04:16:32 gcc 13678 23519
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04:16:32 as 12999 20541
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[...]
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This shows various processes waiting for available CPU during a Linux kernel
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build. By default the output contains delays for more than 10ms.
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These delays can be analyzed in depth with "perf sched" tool, see:
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* http://www.brendangregg.com/blog/2017-03-16/perf-sched.html
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USAGE message:
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# runqslower --help
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Trace high run queue latency.
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USAGE: runqslower [--help] [-p PID] [-t TID] [min_us]
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EXAMPLES:
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runqslower # trace latency higher than 10000 us (default)
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runqslower 1000 # trace latency higher than 1000 us
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runqslower -p 123 # trace pid 123
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runqslower -t 123 # trace tid 123 (use for threads only)
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-p, --pid=PID Process PID to trace
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-t, --tid=TID Thread TID to trace
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-v, --verbose Verbose debug output
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-?, --help Give this help list
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--usage Give a short usage message
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-V, --version Print program version
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Report bugs to <bpf@vger.kernel.org>.
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