Messages in this thread | | | Date | Wed, 18 Nov 2015 12:22:30 +0800 | From | "Wangnan (F)" <> | Subject | Re: [PATCH 0/3] perf tools DWARF libunwind: Add callchain order support |
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Hi Jiri,
On 2015/11/17 23:05, Jiri Olsa wrote: > hi, > as reported by Milian, currently for DWARF unwind (both libdw > and libunwind) we display callchain in callee order only. > > Adding the support to follow callchain order setup to libunwind > DWARF unwinder, so we could get following output for report: > > $ perf record --call-graph dwarf ls > ... > $ perf report --no-children --stdio > > 39.26% ls libc-2.21.so [.] __strcoll_l > | > ---__strcoll_l > mpsort_with_tmp > mpsort_with_tmp > sort_files > main > __libc_start_main > _start > 0 > > $ perf report -g caller --no-children --stdio > ... > 39.26% ls libc-2.21.so [.] __strcoll_l > | > ---0 > _start > __libc_start_main > main > sort_files > mpsort_with_tmp > mpsort_with_tmp > __strcoll_l > > Tested on x86_64. The change is in generic code only, > so it should not affect other archs. Still it would be > nice to have some confirmation.. Wang Nan? ;-) > > It'd be nice to have this for libdw unwind as well, > but it looks like it's out of reach for perf code.. Jan? > > Also available in: > git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git > perf/callchain_1
Thanks for notifying me about this. I have tested it in my environment.
It works well for me except a small behavior changing. Please see below.
Before applying these patch set:
# perf report --no-children --stdio --call-graph=callee # Overhead Command Shared Object Symbol # ........ ....... ................ ......................... # 96.61% a.out [vdso] [.] __vdso_gettimeofday | ---__vdso_gettimeofday funcc funcb funca main __libc_start_main _start
3.38% a.out a.out [.] funcc | ---funcc | --2.70%-- funcb funca main __libc_start_main _start
0.02% pref_re [kernel.vmlinux] [k] sched_clock | ---sched_clock perf_event_nmi_handler nmi_handle ...
And caller:
# ./perf report --no-children --stdio --call-graph=caller # Overhead Command Shared Object Symbol # ........ ....... ................ ......................... # 96.61% a.out [vdso] [.] __vdso_gettimeofday | ---__vdso_gettimeofday funcc funcb funca main __libc_start_main _start
3.38% a.out a.out [.] funcc | ---funcc | --2.70%-- funcb funca main __libc_start_main _start
0.02% pref_re [kernel.vmlinux] [k] sched_clock | ---return_from_execve sys_execve do_execveat_common.isra.27
The user code part of output are identical so I confirm the bug.
After applying this patchset:
# ./perf report --no-children --stdio --call-graph=callee # Overhead Command Shared Object Symbol # ........ ....... ................ ......................... # 96.61% a.out [vdso] [.] __vdso_gettimeofday | ---__vdso_gettimeofday funcc funcb funca main __libc_start_main _start
3.38% a.out a.out [.] funcc | ---funcc | |--2.70%-- funcb | funca | main | __libc_start_main | _start | --0.68%-- 0 0.02% pref_re [kernel.vmlinux] [k] sched_clock | ---sched_clock perf_event_nmi_handler ...
And caller:
# ./perf report --no-children --stdio --call-graph=caller # Overhead Command Shared Object Symbol # ........ ....... ................ ......................... # 96.61% a.out [vdso] [.] __vdso_gettimeofday | ---_start __libc_start_main main funca funcb funcc __vdso_gettimeofday
3.38% a.out a.out [.] funcc | |--2.70%-- _start | __libc_start_main | main | funca | funcb | funcc | --0.68%-- 0 funcc
0.02% pref_re [kernel.vmlinux] [k] sched_clock | ---return_from_execve sys_execve ...
It fixes the bug. However, do you see the extra "0.68%-- 0" in the tree?
I give a message on patch 2/3, please have a look. I think this change would be okay for me if we treat the old behavior as a bug (for example: sum of all branches not equal to the overhead of itself). However, the original code explicitly avoid generating '0' entry so I think we should make it clear.
Thank you.
> thanks, > jirka > > > Cc: Jan Kratochvil <jkratoch@redhat.com> > --- > Jiri Olsa (3): > perf tools: Move initial entry call into get_entries function > perf tools: Add callchain order support for libunwind DWARF unwinder > perf test: Add callchain order setup for DWARF unwinder test > > tools/perf/tests/dwarf-unwind.c | 22 +++++++++++++++++++--- > tools/perf/util/unwind-libunwind.c | 60 +++++++++++++++++++++++++++++++++++++++--------------------- > 2 files changed, 58 insertions(+), 24 deletions(-)
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