[PATCH v4 10/15] perf report: compare symbol name for inlined frames when sorting

Milian Wolff
2017-10-01T14:33:01Z

Similar to the callstack frame matching, we also have to compare
the symbol name when sorting hist entries. The reason is twofold:
On one hand, multiple inlined functions will use the same symbol
start/end values of the parent, non-inlined symbol. As such, all
of these symbols often end up missing from top-level report, as
they get merged with the non-inlined frame. On the other hand,
multiple different functions may end up inlining the same function,
and we need to aggregate these values properly.

Before:

~~~~~
perf report --stdio --inline -g none
# Children Self Command Shared Object Symbol
# ........ ........ ............ ................ ...................................
#
100.00% 39.69% cpp-inlining cpp-inlining [.] main
100.00% 0.00% cpp-inlining cpp-inlining [.] _start
100.00% 0.00% cpp-inlining libc-2.25.so [.] __libc_start_main
97.03% 0.00% cpp-inlining cpp-inlining [.] std::norm<double> (inlined)
59.53% 4.26% cpp-inlining libm-2.25.so [.] hypot
55.21% 55.08% cpp-inlining libm-2.25.so [.] __hypot_finite
0.52% 0.52% cpp-inlining libm-2.25.so [.] cabs
~~~~~

After:

~~~~~
perf report --stdio --inline -g none
# Children Self Command Shared Object Symbol
# ........ ........ ............ ................ ...................................................................................................................................
#
100.00% 39.69% cpp-inlining cpp-inlining [.] main
100.00% 0.00% cpp-inlining cpp-inlining [.] _start
100.00% 0.00% cpp-inlining libc-2.25.so [.] __libc_start_main
62.57% 0.00% cpp-inlining cpp-inlining [.] std::_Norm_helper<true>::_S_do_it<double> (inlined)
62.57% 0.00% cpp-inlining cpp-inlining [.] std::__complex_abs (inlined)
62.57% 0.00% cpp-inlining cpp-inlining [.] std::abs<double> (inlined)
62.57% 0.00% cpp-inlining cpp-inlining [.] std::norm<double> (inlined)
59.53% 4.26% cpp-inlining libm-2.25.so [.] hypot
55.21% 55.08% cpp-inlining libm-2.25.so [.] __hypot_finite
34.46% 0.00% cpp-inlining cpp-inlining [.] std::uniform_real_distribution<double>::operator()<std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > (inlined)
32.39% 0.00% cpp-inlining cpp-inlining [.] std::__detail::_Adaptor<std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul>, double>::operator() (inlined)
32.39% 0.00% cpp-inlining cpp-inlining [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > (inlined)
12.29% 0.00% cpp-inlining cpp-inlining [.] std::__detail::_Mod<unsigned long, 2147483647ul, 16807ul, 0ul, true, true>::__calc (inlined)
12.29% 0.00% cpp-inlining cpp-inlining [.] std::__detail::__mod<unsigned long, 2147483647ul, 16807ul, 0ul> (inlined)
12.29% 0.00% cpp-inlining cpp-inlining [.] std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul>::operator() (inlined)
0.52% 0.52% cpp-inlining libm-2.25.so [.] cabs
~~~~~

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Yao Jin <yao.jin@linux.intel.com>
Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
---
tools/perf/util/sort.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index acb9210fd18a..006d10a0dc96 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -225,6 +225,9 @@ static int64_t _sort__sym_cmp(struct symbol *sym_l, struct symbol *sym_r)
if (sym_l == sym_r)
return 0;

+ if (sym_l->inlined || sym_r->inlined)
+ return strcmp(sym_l->name, sym_r->name);
+
if (sym_l->start != sym_r->start)
return (int64_t)(sym_r->start - sym_l->start);

--
2.14.2