[PATCH 07/41] perf report: Ask for ordered events for --tasks option
From: Arnaldo Carvalho de Melo
Date: Fri Feb 16 2018 - 14:40:00 EST
From: Jiri Olsa <jolsa@xxxxxxxxxx>
If we have the time in, keep the events in time order.
Committer notes:
Trying to be more verbose, what actual effect this will have in this particular
case?
Before and after this patch shows the artifacts:
--- /tmp/before 2018-02-06 15:40:29.536411625 -0300
+++ /tmp/after 2018-02-06 15:40:51.963403599 -0300
@@ -5,34 +5,34 @@
2540 2540 1818 | gnome-terminal-
3489 3489 2540 | bash
32433 32433 3489 | perf
- 32434 32434 32433 | perf
+ 32434 32434 32433 | make
32441 32441 32434 | make
32514 32514 32441 | make
511 511 32514 | sh
- 512 512 511 | sh
+ 512 512 511 | install
<SNIP>
We don't have 'perf' calling 'perf' calling 'make', etc, the second
'perf' actually is 'make', i.e. there was reordering of the relevant
PERF_RECORD_COMM and PERF_RECORD_FORK records.
Ditto for sh/install later on.
Look for FORK and COMM meta events, for those tids:
# perf report -D | egrep 'PERF_RECORD_(FORK|COMM)' | egrep '3243[34]'
0 14774650990679 0x1a3cd8 [0x38]: PERF_RECORD_FORK(32433:32433):(3489:3489)
1 14774652080381 0x1d6568 [0x30]: PERF_RECORD_COMM exec: perf:32433/32433
1 14774742473340 0x1dbb48 [0x38]: PERF_RECORD_FORK(32434:32434):(32433:32433)
0 14774752005779 0x1a4af8 [0x30]: PERF_RECORD_COMM exec: make:32434/32434
0 14774753997960 0x1a5578 [0x38]: PERF_RECORD_FORK(32435:32435):(32434:32434)
0 14774756070782 0x1a5618 [0x38]: PERF_RECORD_FORK(32438:32438):(32434:32434)
0 14774757772939 0x1a5680 [0x38]: PERF_RECORD_FORK(32440:32440):(32434:32434)
0 14774758230600 0x1a56e8 [0x38]: PERF_RECORD_FORK(32441:32441):(32434:32434)
#
First column is the cpu, second is the timestamp.
So they are on different CPUs, thus ring buffers, and when we don't use
the ordered_events class, we end up mixing that up, use it to take
advantage of the PERF_RECORD_FINISHED_ROUND meta events to go on
ordering the events using the PERF_SAMPLE_TIME present in the
PERF_RECORD_{FORK,COMM,EXIT,SAMPLE,etc} records in the ring buffer.
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20180206181813.10943-2-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-report.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 4ad5dc649716..8ef71669e7a0 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -614,6 +614,7 @@ static int stats_print(struct report *rep)
static void tasks_setup(struct report *rep)
{
memset(&rep->tool, 0, sizeof(rep->tool));
+ rep->tool.ordered_events = true;
if (rep->mmaps_mode) {
rep->tool.mmap = perf_event__process_mmap;
rep->tool.mmap2 = perf_event__process_mmap2;
--
2.14.3