On Thu, Jul 20, 2017 at 10:11:57PM -0700, David Carrillo-Cisneros wrote:
> Fixes bug noted by Jiri in https://lkml.org/lkml/2017/6/13/755 and caused
> by commit d49dadea7862 ("perf tools: Make 'trace' or 'trace_fields' sort
> key default for tracepoint events")
> not taking into account that evlist is empty in pipe-mode.
>
> Before this commit, pipe mode will only show bogus "100.00% N/A" instead
> of correct output as follows:
>
> $ perf record -o - sleep 1 | perf report -i -
> # To display the perf.data header info, please use --header/--header-only
> options.
> #
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.000 MB - ]
> #
> # Total Lost Samples: 0
> #
> # Samples: 8 of event 'cycles:ppH'
> # Event count (approx.): 145658
> #
> # Overhead Trace output
> # ........ ............
> #
> 100.00% N/A
>
> Correct output, after patch:
>
> $ perf record -o - sleep 1 | perf report -i -
> # To display the perf.data header info, please use --header/--header-only
> options.
> #
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.000 MB - ]
> #
> # Total Lost Samples: 0
> #
> # Samples: 8 of event 'cycles:ppH'
> # Event count (approx.): 191331
> #
> # Overhead Command Shared Object Symbol
> # ........ ....... ................. .................................
> #
> 81.63% sleep libc-2.19.so [.] _exit
> 13.58% sleep ld-2.19.so [.] do_lookup_x
> 2.34% sleep [kernel.kallsyms] [k] context_switch
> 2.34% sleep libc-2.19.so [.] __GI___libc_nanosleep
> 0.11% perf [kernel.kallsyms] [k] __intel_pmu_enable_a
>
I wonder we could reinit the sortorder once we know what
events we have in pipe, and recognize the tracepoint output
properly:
[root@krava perf]# ./perf record -e 'sched:sched_switch' sleep 1 |
./perf report
# To display the perf.data header info, please use
--header/--header-only options.
SNIP
#
# Overhead Command Shared Object Symbol
# ........ ....... ................. ..............
#
100.00% sleep [kernel.kallsyms] [k] __schedule
also I've got another crash for (added -a option for above example):
[root@krava perf]# ./perf record -e 'sched:sched_switch' -a sleep 1 |
./perf report
# To display the perf.data header info, please use
--header/--header-only options.
#
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.000 MB (null) ]
Segmentation fault (core dumped)
catchsegv got:
/home/jolsa/kernel/linux-perf/tools/perf/util/ordered-events.c:85(free_dup_event)[0x51a6a5]
./perf(ordered_events__free+0x5c)[0x51b0b7]
/home/jolsa/kernel/linux-perf/tools/perf/util/session.c:1751(__perf_session__process_pipe_events)[0x518abb]
./perf(perf_session__process_events+0x91)[0x5190f0]
/home/jolsa/kernel/linux-perf/tools/perf/builtin-report.c:598(__cmd_report)[0x443a91]
./perf(cmd_report+0x169b)[0x4455a3]
/home/jolsa/kernel/linux-perf/tools/perf/perf.c:296(run_builtin)[0x4be1b0]
/home/jolsa/kernel/linux-perf/tools/perf/perf.c:348(handle_internal_command)[0x4be41d]
/home/jolsa/kernel/linux-perf/tools/perf/perf.c:395(run_argv)[0x4be56f]
./perf(main+0x2d6)[0x4be949]
/lib64/libc.so.6(__libc_start_main+0xf1)[0x7f3de8a10401]
./perf(_start+0x2a)[0x42831a]
looks like some mem corruption.. will try to follow up
on this later if nobody beats me to it ;-)
thanks,
jirka
