From cd136189370cc8a5aec0ea4b4ec517e5ee38d8a0 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 3 Jul 2019 10:09:49 +0200 Subject: [PATCH] perf evsel: Do not rely on errno values for precise_ip fallback Konstantin reported problem with default perf record command, which fails on some AMD servers, because of the default maximum precise config. The current fallback mechanism counts on getting ENOTSUP errno for precise_ip fails, but that's not the case on some AMD servers. We can fix this by removing the errno check completely, because the precise_ip fallback is separated. We can just try (if requested by evsel->precise_max) all possible precise_ip, and if one succeeds we win, if not, we continue with standard fallback. Reported-by: Konstantin Kharlamov Signed-off-by: Jiri Olsa Cc: Alexander Shishkin Cc: Andi Kleen Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Quentin Monnet Cc: Kim Phillips Link: http://lkml.kernel.org/r/20190703080949.10356-1-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evsel.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 4a5947625c5c..69beb9f80f07 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1785,14 +1785,8 @@ static int perf_event_open(struct perf_evsel *evsel, if (fd >= 0) break; - /* - * Do quick precise_ip fallback if: - * - there is precise_ip set in perf_event_attr - * - maximum precise is requested - * - sys_perf_event_open failed with ENOTSUP error, - * which is associated with wrong precise_ip - */ - if (!precise_ip || !evsel->precise_max || (errno != ENOTSUP)) + /* Do not try less precise if not requested. */ + if (!evsel->precise_max) break; /*