Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:

User visible changes:

  - Adding a field via 'perf report -F' that already is enabled makes
    the tool get stuck in a loop, fix it. (Jiri Olsa)

Infrastructure changes:

  - Support PERF_RECORD_SWITCH in the python binding. (Arnaldo Carvalho de Melo)

  - Fix handling read() result using a signed variable, found with Coccinelle.
    (Andrzej Hajda)

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 20 insertions, 3 deletions

diff --git a/tools/perf/python/twatch.py b/tools/perf/python/twatch.py
index b9d508336ae6..c235c22b107a 100755
--- a/tools/perf/python/twatch.py
+++ b/tools/perf/python/twatch.py
@@ -15,14 +15,14 @@
 
 import perf
 
-def main():
+def main(context_switch = 0, thread = -1):
 	cpus = perf.cpu_map()
-	threads = perf.thread_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,
+			   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,
@@ -48,4 +48,21 @@ def main():
 			print 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()