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>

4 files changed, 37 insertions, 37 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index a4b97269cfc6..b8d0a39b484e 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -224,6 +224,7 @@ static bool perf_evlist__equal(struct perf_evlist *evlist,
 
 static int perf_record__open(struct perf_record *rec)
 {
+        char msg[128];
         struct perf_evsel *pos;
         struct perf_evlist *evlist = rec->evlist;
         struct perf_session *session = rec->session;
@@ -249,27 +250,9 @@ try_again:
                                 goto out;
                         }
 
-                        /*
-                         * 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).
-                         */
-                        if ((err == ENOENT || err == ENXIO)
-                                        && attr->type == PERF_TYPE_HARDWARE
-                                        && attr->config == PERF_COUNT_HW_CPU_CYCLES) {
-
+                        if (perf_evsel__fallback(pos, err, msg, sizeof(msg))) {
                                 if (verbose)
-                                        ui__warning("The cycles event is not supported, "
-                                                    "trying to fall back to cpu-clock-ticks\n");
-                                attr->type = PERF_TYPE_SOFTWARE;
-                                attr->config = PERF_COUNT_SW_CPU_CLOCK;
-                                if (pos->name) {
-                                        free(pos->name);
-                                        pos->name = NULL;
-                                }
+                                        ui__warning("%s\n", msg);
                                 goto try_again;
                         }
 
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 74fca619fc4e..8d41d0b58956 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -892,6 +892,7 @@ static void perf_top__mmap_read(struct perf_top *top)
 
 static void perf_top__start_counters(struct perf_top *top)
 {
+        char msg[128];
         struct perf_evsel *counter;
         struct perf_evlist *evlist = top->evlist;
         struct perf_record_opts *opts = &top->record_opts;
@@ -909,25 +910,10 @@ try_again:
                                 ui__error_paranoid();
                                 goto out_err;
                         }
-                        /*
-                         * If it's cycles then fall back to hrtimer
-                         * based cpu-clock-tick sw counter, which
-                         * is always available even if no PMU support:
-                         */
-                        if ((err == ENOENT || err == ENXIO) &&
-                            (attr->type == PERF_TYPE_HARDWARE) &&
-                            (attr->config == PERF_COUNT_HW_CPU_CYCLES)) {
 
+                        if (perf_evsel__fallback(counter, err, msg, sizeof(msg))) {
                                 if (verbose)
-                                        ui__warning("Cycles event not supported,\n"
-                                                    "trying to fall back to cpu-clock-ticks\n");
-
-                                attr->type = PERF_TYPE_SOFTWARE;
-                                attr->config = PERF_COUNT_SW_CPU_CLOCK;
-                                if (counter->name) {
-                                        free(counter->name);
-                                        counter->name = NULL;
-                                }
+                                        ui__warning("%s\n", msg);
                                 goto try_again;
                         }
 
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index ee6ee3f45c2a..0c88e5c12dab 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1378,3 +1378,31 @@ int perf_evsel__fprintf(struct perf_evsel *evsel,
         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;
+}
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 9cb8a0215711..26d8cfd86e0a 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -251,4 +251,7 @@ struct perf_attr_details {
 
 int perf_evsel__fprintf(struct perf_evsel *evsel,
                         struct perf_attr_details *details, FILE *fp);
+
+bool perf_evsel__fallback(struct perf_evsel *evsel, int err,
+                          char *msg, size_t msgsize);
 #endif /* __PERF_EVSEL_H */