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| 2 | |
| 3 | |
| 4 | |
| 5 | |
| 6 | |
| 7 | |
| 8 |
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| 9 | import perf
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| 10 |
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| 11 | def main(context_switch = 0, thread = -1):
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| 12 | cpus = perf.cpu_map()
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| 13 | threads = perf.thread_map(thread)
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| 14 | evsel = perf.evsel(type = perf.TYPE_SOFTWARE,
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| 15 | config = perf.COUNT_SW_DUMMY,
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| 16 | task = 1, comm = 1, mmap = 0, freq = 0,
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| 17 | wakeup_events = 1, watermark = 1,
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| 18 | sample_id_all = 1, context_switch = context_switch,
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| 19 | sample_type = perf.SAMPLE_PERIOD | perf.SAMPLE_TID | perf.SAMPLE_CPU)
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| 20 |
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| 21 | |
| 22 | using the default, PERF_TYPE_HARDWARE + PERF_COUNT_HW_CYCLES & freq=1
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| 23 | (the default), makes perf reenable irq_vectors:local_timer_entry, when
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| 24 | disabling nohz, not good for some use cases where all we want is to get
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| 25 | threads comes and goes... So use (perf.TYPE_SOFTWARE, perf_COUNT_SW_DUMMY,
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| 26 | freq=0) instead.
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| 27 |
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| 28 | evsel.open(cpus = cpus, threads = threads);
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| 29 | evlist = perf.evlist(cpus, threads)
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| 30 | evlist.add(evsel)
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| 31 | evlist.mmap()
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| 32 | while True:
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| 33 | evlist.poll(timeout = -1)
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| 34 | for cpu in cpus:
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| 35 | event = evlist.read_on_cpu(cpu)
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| 36 | if not event:
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| 37 | continue
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| 38 | print("cpu: {0}, pid: {1}, tid: {2} {3}".format(event.sample_cpu,
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| 39 | event.sample_pid,
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| 40 | event.sample_tid,
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| 41 | event))
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| 42 |
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| 43 | if __name__ == '__main__':
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| 44 | |
| 45 | To test the PERF_RECORD_SWITCH record, pick a pid and replace
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| 46 | in the following line.
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| 47 |
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| 48 | Example output:
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| 49 |
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| 50 | cpu: 3, pid: 31463, tid: 31593 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31593, switch_out: 1 }
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| 51 | cpu: 1, pid: 31463, tid: 31489 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31489, switch_out: 1 }
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| 52 | cpu: 2, pid: 31463, tid: 31496 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31496, switch_out: 1 }
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| 53 | cpu: 3, pid: 31463, tid: 31491 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31491, switch_out: 0 }
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| 54 |
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| 55 | It is possible as well to use event.misc & perf.PERF_RECORD_MISC_SWITCH_OUT
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| 56 | to figure out if this is a context switch in or out of the monitored threads.
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| 57 |
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| 58 | If bored, please add command line option parsing support for these options :-)
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| 59 |
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| 60 | |
| 61 | main()
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