linux-kernel - [PATCH RESEND 2/2] perf tool: evsel: say which PMU Hardware event doesn't support sampling/overflow-interrupts

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Message-Id: <20171114150452.e846f2e23684c7d7d8ee706f@arm.com>
Date:   Tue, 14 Nov 2017 15:04:52 -0600
From:   Kim Phillips <kim.phillips@....com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH RESEND 2/2] perf tool: evsel: say which PMU Hardware event
 doesn't support sampling/overflow-interrupts

Help identify to the user the event with the unsupported sampling
error.  Also suggest a corrective action.

BEFORE:

$ sudo ./oldperf record -e armv8_pmuv3/mem_access/,ccn/cycles/,armv8_pmuv3/l2d_cache/ true
Error:
PMU Hardware doesn't support sampling/overflow-interrupts.

AFTER:

$ sudo ./newperf record -e armv8_pmuv3/mem_access/,ccn/cycles/,armv8_pmuv3/l2d_cache/ true
Error:
ccn/cycles/: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'

Signed-off-by: Kim Phillips <kim.phillips@....com>
---
 tools/perf/util/evsel.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index f894893c203d..a0f298726324 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2739,8 +2739,9 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target,
 		break;
 	case EOPNOTSUPP:
 		if (evsel->attr.sample_period != 0)
-			return scnprintf(msg, size, "%s",
-	"PMU Hardware doesn't support sampling/overflow-interrupts.");
+			return scnprintf(msg, size,
+	"%s: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'",
+					 perf_evsel__name(evsel));
 		if (evsel->attr.precise_ip)
 			return scnprintf(msg, size, "%s",
 	"\'precise\' request may not be supported. Try removing 'p' modifier.");
-- 
2.14.2