From 9856240ad3269f2fdab0b2fa4400ef8aab792061 Mon Sep 17 00:00:00 2001 From: Milian Wolff Date: Mon, 9 Oct 2017 22:33:03 +0200 Subject: perf callchain: Compare symbol name for inlined frames when matching The fake symbols we create for inlined frames will represent different functions but can use the symbol start address. This leads to issues when different inline branches all lead to the same function. Before: ~~~~~ $ perf report -s sym -i perf.inlining.data --inline --stdio -g function ... --38.86%--_start __libc_start_main main | --37.57%--std::norm (inlined) std::_Norm_helper::_S_do_it (inlined) | --36.36%--std::abs (inlined) std::__complex_abs (inlined) | --12.24%--std::linear_congruential_engine::operator() (inlined) std::__detail::__mod (inlined) std::__detail::_Mod::__calc (inlined) ~~~~~ Note that this backtrace representation is completely bogus. Complex abs does not call the linear congruential engine! It is just a side-effect of a longer inlined stack being appended to a shorter, different inlined stack, both of which originate in the same function (main). This patch fixes the issue: ~~~~~ $ perf report -s sym -i perf.inlining.data --inline --stdio -g function ... --38.86%--_start __libc_start_main main | |--35.59%--std::uniform_real_distribution::operator() > (inlined) | std::uniform_real_distribution::operator() > (inlined) | | | --34.37%--std::__detail::_Adaptor, double>::operator() (inlined) | std::generate_canonical > (inlined) | | | --12.24%--std::linear_congruential_engine::operator() (inlined) | std::__detail::__mod (inlined) | std::__detail::_Mod::__calc (inlined) | --1.99%--std::norm (inlined) std::_Norm_helper::_S_do_it (inlined) std::abs (inlined) std::__complex_abs (inlined) ~~~~~ Signed-off-by: Milian Wolff Reviewed-by: Jiri Olsa Reviewed-by: Namhyung Kim Cc: David Ahern Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Yao Jin Link: http://lkml.kernel.org/r/20171009203310.17362-10-milian.wolff@kdab.com Cc: Arnaldo Carvalho de Melo [ Fix up conflict with c1fbc0cf81f1 ("perf callchain: Compare dsos (as well) for CCKEY_FUNCTION"), remove unneeded hunk ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/callchain.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'tools/perf') diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c index 77031efdca5c..35a920f09503 100644 --- a/tools/perf/util/callchain.c +++ b/tools/perf/util/callchain.c @@ -690,6 +690,14 @@ static enum match_result match_chain(struct callchain_cursor_node *node, } if (cnode->ms.sym && sym && callchain_param.key == CCKEY_FUNCTION) { + /* + * Compare inlined frames based on their symbol name because + * different inlined frames will have the same symbol start + */ + if (cnode->ms.sym->inlined || node->sym->inlined) + return match_chain_strings(cnode->ms.sym->name, + node->sym->name); + left = cnode->ms.sym->start; right = sym->start; left_dso = cnode->ms.map->dso; -- cgit v1.2.3