1#! /usr/bin/python 2# -*- python -*- 3# -*- coding: utf-8 -*- 4# twatch - Experimental use of the perf python interface 5# Copyright (C) 2011 Arnaldo Carvalho de Melo <acme@redhat.com> 6# 7# This application is free software; you can redistribute it and/or 8# modify it under the terms of the GNU General Public License 9# as published by the Free Software Foundation; version 2. 10# 11# This application is distributed in the hope that it will be useful, 12# but WITHOUT ANY WARRANTY; without even the implied warranty of 13# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14# General Public License for more details. 15 16import perf 17 18def main(context_switch = 0, thread = -1): 19 cpus = perf.cpu_map() 20 threads = perf.thread_map(thread) 21 evsel = perf.evsel(type = perf.TYPE_SOFTWARE, 22 config = perf.COUNT_SW_DUMMY, 23 task = 1, comm = 1, mmap = 0, freq = 0, 24 wakeup_events = 1, watermark = 1, 25 sample_id_all = 1, context_switch = context_switch, 26 sample_type = perf.SAMPLE_PERIOD | perf.SAMPLE_TID | perf.SAMPLE_CPU) 27 28 """What we want are just the PERF_RECORD_ lifetime events for threads, 29 using the default, PERF_TYPE_HARDWARE + PERF_COUNT_HW_CYCLES & freq=1 30 (the default), makes perf reenable irq_vectors:local_timer_entry, when 31 disabling nohz, not good for some use cases where all we want is to get 32 threads comes and goes... So use (perf.TYPE_SOFTWARE, perf_COUNT_SW_DUMMY, 33 freq=0) instead.""" 34 35 evsel.open(cpus = cpus, threads = threads); 36 evlist = perf.evlist(cpus, threads) 37 evlist.add(evsel) 38 evlist.mmap() 39 while True: 40 evlist.poll(timeout = -1) 41 for cpu in cpus: 42 event = evlist.read_on_cpu(cpu) 43 if not event: 44 continue 45 print "cpu: %2d, pid: %4d, tid: %4d" % (event.sample_cpu, 46 event.sample_pid, 47 event.sample_tid), 48 print event 49 50if __name__ == '__main__': 51 """ 52 To test the PERF_RECORD_SWITCH record, pick a pid and replace 53 in the following line. 54 55 Example output: 56 57cpu: 3, pid: 31463, tid: 31593 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31593, switch_out: 1 } 58cpu: 1, pid: 31463, tid: 31489 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31489, switch_out: 1 } 59cpu: 2, pid: 31463, tid: 31496 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31496, switch_out: 1 } 60cpu: 3, pid: 31463, tid: 31491 { type: context_switch, next_prev_pid: 31463, next_prev_tid: 31491, switch_out: 0 } 61 62 It is possible as well to use event.misc & perf.PERF_RECORD_MISC_SWITCH_OUT 63 to figure out if this is a context switch in or out of the monitored threads. 64 65 If bored, please add command line option parsing support for these options :-) 66 """ 67 # main(context_switch = 1, thread = 31463) 68 main() 69