perf evlist: Steal mmap reading routine from 'perf top'

Will be used in the upcoming 'perf test' entry for the evlist mmap
routines.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 3 insertions, 53 deletions

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index df85c1f9417b..58352ad807c7 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1100,67 +1100,17 @@ static void event__process_sample(const event_t *self,
 
 static void perf_session__mmap_read_cpu(struct perf_session *self, int cpu)
 {
-        struct perf_mmap *md = &evsel_list->mmap[cpu];
-        unsigned int head = perf_mmap__read_head(md);
-        unsigned int old = md->prev;
-        unsigned char *data = md->base + page_size;
         struct sample_data sample;
-        int diff;
-
-        /*
-         * If we're further behind than half the buffer, there's a chance
-         * the writer will bite our tail and mess up the samples under us.
-         *
-         * If we somehow ended up ahead of the head, we got messed up.
-         *
-         * In either case, truncate and restart at head.
-         */
-        diff = head - old;
-        if (diff > md->mask / 2 || diff < 0) {
-                fprintf(stderr, "WARNING: failed to keep up with mmap data.\n");
-
-                /*
-                 * head points to a known good entry, start there.
-                 */
-                old = head;
-        }
-
-        for (; old != head;) {
-                event_t *event = (event_t *)&data[old & md->mask];
-
-                event_t event_copy;
-
-                size_t size = event->header.size;
-
-                /*
-                 * Event straddles the mmap boundary -- header should always
-                 * be inside due to u64 alignment of output.
-                 */
-                if ((old & md->mask) + size != ((old + size) & md->mask)) {
-                        unsigned int offset = old;
-                        unsigned int len = min(sizeof(*event), size), cpy;
-                        void *dst = &event_copy;
-
-                        do {
-                                cpy = min(md->mask + 1 - (offset & md->mask), len);
-                                memcpy(dst, &data[offset & md->mask], cpy);
-                                offset += cpy;
-                                dst += cpy;
-                                len -= cpy;
-                        } while (len);
-
-                        event = &event_copy;
-                }
+        event_t *event;
 
+        while ((event = perf_evlist__read_on_cpu(evsel_list, cpu)) != NULL) {
                 event__parse_sample(event, self, &sample);
+
                 if (event->header.type == PERF_RECORD_SAMPLE)
                         event__process_sample(event, &sample, self);
                 else
                         event__process(event, &sample, self);
-                old += size;
         }
-
-        md->prev = old;
 }
 
 static void perf_session__mmap_read(struct perf_session *self)