From ed6c166cc7dc329736cace3affd2df984fb22ec8 Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Tue, 13 Dec 2016 10:29:44 -0500 Subject: [PATCH] perf diff: Do not overwrite valid build id Fixes a perf diff regression issue which was introduced by commit 5baecbcd9c9a ("perf symbols: we can now read separate debug-info files based on a build ID") The binary name could be same when perf diff different binaries. Build id is used to distinguish between them. However, the previous patch assumes the same binary name has same build id. So it overwrites the build id according to the binary name, regardless of whether the build id is set or not. Check the has_build_id in dso__load. If the build id is already set, use it. Before the fix: $ perf diff 1.perf.data 2.perf.data # Event 'cycles' # # Baseline Delta Shared Object Symbol # ........ ....... ................ ............................. # 99.83% -99.80% tchain_edit [.] f2 0.12% +99.81% tchain_edit [.] f3 0.02% -0.01% [ixgbe] [k] ixgbe_read_reg After the fix: $ perf diff 1.perf.data 2.perf.data # Event 'cycles' # # Baseline Delta Shared Object Symbol # ........ ....... ................ ............................. # 99.83% +0.10% tchain_edit [.] f3 0.12% -0.08% tchain_edit [.] f2 Signed-off-by: Kan Liang Cc: Andi Kleen CC: Dima Kogan Cc: Jiri Olsa Cc: Namhyung Kim Fixes: 5baecbcd9c9a ("perf symbols: we can now read separate debug-info files based on a build ID") Link: http://lkml.kernel.org/r/1481642984-13593-1-git-send-email-kan.liang@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/symbol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index df2482b2ba45..dc93940de351 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -1459,7 +1459,8 @@ int dso__load(struct dso *dso, struct map *map) * Read the build id if possible. This is required for * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work */ - if (is_regular_file(dso->long_name) && + if (!dso->has_build_id && + is_regular_file(dso->long_name) && filename__read_build_id(dso->long_name, build_id, BUILD_ID_SIZE) > 0) dso__set_build_id(dso, build_id); -- 2.39.5