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-rwxr-xr-xtools/perf/python/twatch.py61
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diff --git a/tools/perf/python/twatch.py b/tools/perf/python/twatch.py
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+#! /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()