From 8f431a28696d27e3370ebd1a5fd1681a8c773a8e Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 7 Mar 2022 17:19:14 +0000 Subject: perf evsel: Add error message for unsupported branch stack cases EOPNOTSUPP is a possible return value when branch stacks are requested but they aren't enabled in the kernel or hardware. It's also returned if they aren't supported on the specific event type. The currently printed error message about sampling/overflow-interrupts is not correct in this case. Add a check for branch stacks before sample_period is checked because sample_period is also set (to the default value) when using branch stacks. Before this change (when branch stacks aren't supported): perf record -j any Error: cycles: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat' After this change: perf record -j any Error: cycles: PMU Hardware or event type doesn't support branch stack sampling. Signed-off-by: James Clark Cc: Alexander Shishkin Cc: Anshuman Khandual Cc: German Gomez Cc: Jiri Olsa Cc: Leo Yan Cc: Mark Rutland Cc: Namhyung Kim Link: https://lore.kernel.org/r/20220307171917.2555829-2-james.clark@arm.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evsel.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'tools/perf/util/evsel.c') diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 22d3267ce294..4e10a4ec11c7 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -2909,6 +2909,10 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target, "No such device - did you specify an out-of-range profile CPU?"); break; case EOPNOTSUPP: + if (evsel->core.attr.sample_type & PERF_SAMPLE_BRANCH_STACK) + return scnprintf(msg, size, + "%s: PMU Hardware or event type doesn't support branch stack sampling.", + evsel__name(evsel)); if (evsel->core.attr.aux_output) return scnprintf(msg, size, "%s: PMU Hardware doesn't support 'aux_output' feature", -- cgit