perf record: Move probing cgroup sampling support

I found that checking cgroup sampling support using the missing features
doesn't work on old kernels.  Because it added both attr.cgroup bit and
PERF_SAMPLE_CGROUP bit, it needs to check whichever comes first (usually
the actual event, not dummy).

But it only checks the attr.cgroup bit which is set only in the dummy
event so cannot detect failtures due the sample bits.  Also we don't
ignore the missing feature and retry, it'd be better checking it with
the API probing logic.

Committer notes:

Extracted the minimal part to check using the new cgroup API probe
routine, the part that removes the cgroup member can be left for further
discussion.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210527182835.1634339-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 3337b5f93336d945cee5e2febfae2b0116e24d1b..84803abeb94251b737200901ba64f91ed67edfd6 100644 (file)
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -2714,6 +2714,12 @@ int cmd_record(int argc, const char **argv)
                rec->no_buildid = true;
        }
 
+       if (rec->opts.record_cgroup && !perf_can_record_cgroup()) {
+               pr_err("Kernel has no cgroup sampling support.\n");
+               err = -EINVAL;
+               goto out_opts;
+       }
+
        if (rec->opts.kcore)
                rec->data.is_dir = true;
 

diff --git a/tools/perf/util/perf_api_probe.c b/tools/perf/util/perf_api_probe.c
index 829af17a0867b2c766620db692e1a97393a61a34..020411682a3cb433cd2fb6c96eaa27a1e2484e23 100644 (file)
--- a/tools/perf/util/perf_api_probe.c
+++ b/tools/perf/util/perf_api_probe.c
@@ -103,6 +103,11 @@ static void perf_probe_build_id(struct evsel *evsel)
        evsel->core.attr.build_id = 1;
 }
 
+static void perf_probe_cgroup(struct evsel *evsel)
+{
+       evsel->core.attr.cgroup = 1;
+}
+
 bool perf_can_sample_identifier(void)
 {
        return perf_probe_api(perf_probe_sample_identifier);
@@ -182,3 +187,8 @@ bool perf_can_record_build_id(void)
 {
        return perf_probe_api(perf_probe_build_id);
 }
+
+bool perf_can_record_cgroup(void)
+{
+       return perf_probe_api(perf_probe_cgroup);
+}

diff --git a/tools/perf/util/perf_api_probe.h b/tools/perf/util/perf_api_probe.h
index f12ca55f509a8386986a04dc74f6a0abbf6ddb89..b104168efb154d5c8fb24aacea66b951867f7a9a 100644 (file)
--- a/tools/perf/util/perf_api_probe.h
+++ b/tools/perf/util/perf_api_probe.h
@@ -12,5 +12,6 @@ bool perf_can_record_switch_events(void);
 bool perf_can_record_text_poke_events(void);
 bool perf_can_sample_identifier(void);
 bool perf_can_record_build_id(void);
+bool perf_can_record_cgroup(void);
 
 #endif // __PERF_API_PROBE_H