perf evsel: Introduce event fallback method
The only fallback right now is for HW cpu-cycles -> SW cpu-clock, that
was done in the same way in both 'top' and 'record'.
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-58l1mgibh9oa9m0pd3fasxa5@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index ee6ee3f..0c88e5c 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1378,3 +1378,31 @@
fputc('\n', fp);
return ++printed;
}
+
+bool perf_evsel__fallback(struct perf_evsel *evsel, int err,
+ char *msg, size_t msgsize)
+{
+ if ((err == ENOENT || err == ENXIO) &&
+ evsel->attr.type == PERF_TYPE_HARDWARE &&
+ evsel->attr.config == PERF_COUNT_HW_CPU_CYCLES) {
+ /*
+ * If it's cycles then fall back to hrtimer based
+ * cpu-clock-tick sw counter, which is always available even if
+ * no PMU support.
+ *
+ * PPC returns ENXIO until 2.6.37 (behavior changed with commit
+ * b0a873e).
+ */
+ scnprintf(msg, msgsize, "%s",
+"The cycles event is not supported, trying to fall back to cpu-clock-ticks");
+
+ evsel->attr.type = PERF_TYPE_SOFTWARE;
+ evsel->attr.config = PERF_COUNT_SW_CPU_CLOCK;
+
+ free(evsel->name);
+ evsel->name = NULL;
+ return true;
+ }
+
+ return false;
+}