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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162#! /usr/bin/env python# SPDX-License-Identifier: GPL-2.0-only# -*- python -*-# -*- coding: utf-8 -*-# twatch - Experimental use of the perf python interface# Copyright (C) 2011 Arnaldo Carvalho de Melo <acme@redhat.com>#
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()