mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-09-17 09:41:09 +02:00
Jiri Olsa
8614ada0be
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@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180206181813.10943-2-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.