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Diffstat (limited to 'tools/perf/python/twatch.py')
| -rwxr-xr-x | tools/perf/python/twatch.py | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/tools/perf/python/twatch.py b/tools/perf/python/twatch.py new file mode 100755 index 000000000..0a29c5c30 --- /dev/null +++ b/tools/perf/python/twatch.py @@ -0,0 +1,68 @@ +#! /usr/bin/python +# -*- python -*- +# -*- coding: utf-8 -*- +# twatch - Experimental use of the perf python interface +# Copyright (C) 2011 Arnaldo Carvalho de Melo <acme@redhat.com> +# +# This application is free software; you can redistribute it and/or +# modify it under the terms of the GNU General Public License +# as published by the Free Software Foundation; version 2. +# +# This application is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# General Public License for more details. + +import perf + +def main(context_switch = 0, thread = -1): + cpus = perf.cpu_map() + threads = perf.thread_map(thread) + evsel = perf.evsel(type = perf.TYPE_SOFTWARE, + config = perf.COUNT_SW_DUMMY, + task = 1, comm = 1, mmap = 0, freq = 0, + wakeup_events = 1, watermark = 1, + sample_id_all = 1, context_switch = context_switch, + sample_type = perf.SAMPLE_PERIOD | perf.SAMPLE_TID | perf.SAMPLE_CPU) + + """What we want are just the PERF_RECORD_ lifetime events for threads, + using the default, PERF_TYPE_HARDWARE + PERF_COUNT_HW_CYCLES & freq=1 + (the default), makes perf reenable irq_vectors:local_timer_entry, when + disabling nohz, not good for some use cases where all we want is to get + threads comes and goes... So use (perf.TYPE_SOFTWARE, perf_COUNT_SW_DUMMY, + freq=0) instead.""" + + evsel.open(cpus = cpus, threads = threads); + evlist = perf.evlist(cpus, threads) + evlist.add(evsel) + evlist.mmap() + while True: + evlist.poll(timeout = -1) + for cpu in cpus: + event = evlist.read_on_cpu(cpu) + if not event: + continue + print("cpu: {0}, pid: {1}, tid: {2} {3}".format(event.sample_cpu, + event.sample_pid, + event.sample_tid, + event)) + +if __name__ == '__main__': + """ + To test the PERF_RECORD_SWITCH record, pick a pid and replace + in the following line. + + Example output: + +cpu: 3, pid: 31463, tid: 31593 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31593, switch_out: 1 } +cpu: 1, pid: 31463, tid: 31489 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31489, switch_out: 1 } +cpu: 2, pid: 31463, tid: 31496 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31496, switch_out: 1 } +cpu: 3, pid: 31463, tid: 31491 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31491, switch_out: 0 } + + It is possible as well to use event.misc & perf.PERF_RECORD_MISC_SWITCH_OUT + to figure out if this is a context switch in or out of the monitored threads. + + If bored, please add command line option parsing support for these options :-) + """ + # main(context_switch = 1, thread = 31463) + main() |