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| author | Milian Wolff <milian.wolff@kdab.com> | 2017-06-02 00:00:21 +0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2017-06-05 20:18:03 +0300 |
| commit | 5ea0416f51cc93436bbe497c62ab49fd9cb245b6 (patch) | |
| tree | 931608caf53e6c45bbb8f38b89cc34f03d958455 /tools | |
| parent | 6db47fdec7562b02703e346c10f7f4efdda6af5a (diff) | |
| download | linux-5ea0416f51cc93436bbe497c62ab49fd9cb245b6.tar.xz | |
perf report: Include partial stacks unwound with libdw
So far the whole stack was thrown away when any error occurred before
the maximum stack depth was unwound. This is actually a very common
scenario though. The stacks that got unwound so far are still
interesting. This removes a large chunk of differences when comparing
perf script output for libunwind and libdw perf unwinding.
E.g. with libunwind:
~~~~~
heaptrack_gui 2228 135073.388524: 479408 cycles:
ffffffff811749ed perf_iterate_ctx ([kernel.kallsyms])
ffffffff81181662 perf_event_mmap ([kernel.kallsyms])
ffffffff811cf5ed mmap_region ([kernel.kallsyms])
ffffffff811cfe6b do_mmap ([kernel.kallsyms])
ffffffff811b0dca vm_mmap_pgoff ([kernel.kallsyms])
ffffffff811cdb0c sys_mmap_pgoff ([kernel.kallsyms])
ffffffff81033acb sys_mmap ([kernel.kallsyms])
ffffffff81631d37 entry_SYSCALL_64_fastpath ([kernel.kallsyms])
192ca mmap64 (/usr/lib/ld-2.25.so)
59a9 _dl_map_object_from_fd (/usr/lib/ld-2.25.so)
83d0 _dl_map_object (/usr/lib/ld-2.25.so)
cda1 openaux (/usr/lib/ld-2.25.so)
1834f _dl_catch_error (/usr/lib/ld-2.25.so)
cfe2 _dl_map_object_deps (/usr/lib/ld-2.25.so)
3481 dl_main (/usr/lib/ld-2.25.so)
17387 _dl_sysdep_start (/usr/lib/ld-2.25.so)
4d37 _dl_start (/usr/lib/ld-2.25.so)
d87 _start (/usr/lib/ld-2.25.so)
heaptrack_gui 2228 135073.388677: 611329 cycles:
1a3e0 strcmp (/usr/lib/ld-2.25.so)
82b2 _dl_map_object (/usr/lib/ld-2.25.so)
cda1 openaux (/usr/lib/ld-2.25.so)
1834f _dl_catch_error (/usr/lib/ld-2.25.so)
cfe2 _dl_map_object_deps (/usr/lib/ld-2.25.so)
3481 dl_main (/usr/lib/ld-2.25.so)
17387 _dl_sysdep_start (/usr/lib/ld-2.25.so)
4d37 _dl_start (/usr/lib/ld-2.25.so)
d87 _start (/usr/lib/ld-2.25.so)
~~~~~
With libdw without this patch:
~~~~~
heaptrack_gui 2228 135073.388524: 479408 cycles:
ffffffff811749ed perf_iterate_ctx ([kernel.kallsyms])
ffffffff81181662 perf_event_mmap ([kernel.kallsyms])
ffffffff811cf5ed mmap_region ([kernel.kallsyms])
ffffffff811cfe6b do_mmap ([kernel.kallsyms])
ffffffff811b0dca vm_mmap_pgoff ([kernel.kallsyms])
ffffffff811cdb0c sys_mmap_pgoff ([kernel.kallsyms])
ffffffff81033acb sys_mmap ([kernel.kallsyms])
ffffffff81631d37 entry_SYSCALL_64_fastpath ([kernel.kallsyms])
heaptrack_gui 2228 135073.388677: 611329 cycles:
~~~~~
With this patch applied, the libdw unwinder will produce the same
output as the libunwind unwinder.
Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20170601210021.20046-1-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/perf/util/unwind-libdw.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c index 943a06291587..b4c20124d2ee 100644 --- a/tools/perf/util/unwind-libdw.c +++ b/tools/perf/util/unwind-libdw.c @@ -224,7 +224,7 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg, err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui); - if (err && !ui->max_stack) + if (err && ui->max_stack != max_stack) err = 0; /* |