1 files changed, 87 insertions, 38 deletions

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 71bc608e0ec6..c088d8f9b51c 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -98,7 +98,6 @@ struct perf_session *perf_session__new(const char *filename, int mode, bool forc
         self->unknown_events = 0;
         self->machines = RB_ROOT;
         self->repipe = repipe;
-        self->ordered_samples.flush_limit = ULLONG_MAX;
         INIT_LIST_HEAD(&self->ordered_samples.samples_head);
         machine__init(&self->host_machine, "", HOST_KERNEL_ID);
 
@@ -195,6 +194,18 @@ static int process_event_stub(event_t *event __used,
         return 0;
 }
 
+static int process_finished_round_stub(event_t *event __used,
+                                       struct perf_session *session __used,
+                                       struct perf_event_ops *ops __used)
+{
+        dump_printf(": unhandled!\n");
+        return 0;
+}
+
+static int process_finished_round(event_t *event,
+                                  struct perf_session *session,
+                                  struct perf_event_ops *ops);
+
 static void perf_event_ops__fill_defaults(struct perf_event_ops *handler)
 {
         if (handler->sample == NULL)
@@ -223,6 +234,12 @@ static void perf_event_ops__fill_defaults(struct perf_event_ops *handler)
                 handler->tracing_data = process_event_stub;
         if (handler->build_id == NULL)
                 handler->build_id = process_event_stub;
+        if (handler->finished_round == NULL) {
+                if (handler->ordered_samples)
+                        handler->finished_round = process_finished_round;
+                else
+                        handler->finished_round = process_finished_round_stub;
+        }
 }
 
 static const char *event__name[] = {
@@ -360,16 +377,14 @@ struct sample_queue {
         struct list_head        list;
 };
 
-#define FLUSH_PERIOD    (2 * NSEC_PER_SEC)
-
 static void flush_sample_queue(struct perf_session *s,
                                struct perf_event_ops *ops)
 {
         struct list_head *head = &s->ordered_samples.samples_head;
-        u64 limit = s->ordered_samples.flush_limit;
+        u64 limit = s->ordered_samples.next_flush;
         struct sample_queue *tmp, *iter;
 
-        if (!ops->ordered_samples)
+        if (!ops->ordered_samples || !limit)
                 return;
 
         list_for_each_entry_safe(iter, tmp, head, list) {
@@ -388,6 +403,55 @@ static void flush_sample_queue(struct perf_session *s,
         }
 }
 
+/*
+ * When perf record finishes a pass on every buffers, it records this pseudo
+ * event.
+ * We record the max timestamp t found in the pass n.
+ * Assuming these timestamps are monotonic across cpus, we know that if
+ * a buffer still has events with timestamps below t, they will be all
+ * available and then read in the pass n + 1.
+ * Hence when we start to read the pass n + 2, we can safely flush every
+ * events with timestamps below t.
+ *
+ *    ============ PASS n =================
+ *       CPU 0         |   CPU 1
+ *                     |
+ *    cnt1 timestamps  |   cnt2 timestamps
+ *          1          |         2
+ *          2          |         3
+ *          -          |         4  <--- max recorded
+ *
+ *    ============ PASS n + 1 ==============
+ *       CPU 0         |   CPU 1
+ *                     |
+ *    cnt1 timestamps  |   cnt2 timestamps
+ *          3          |         5
+ *          4          |         6
+ *          5          |         7 <---- max recorded
+ *
+ *      Flush every events below timestamp 4
+ *
+ *    ============ PASS n + 2 ==============
+ *       CPU 0         |   CPU 1
+ *                     |
+ *    cnt1 timestamps  |   cnt2 timestamps
+ *          6          |         8
+ *          7          |         9
+ *          -          |         10
+ *
+ *      Flush every events below timestamp 7
+ *      etc...
+ */
+static int process_finished_round(event_t *event __used,
+                                  struct perf_session *session,
+                                  struct perf_event_ops *ops)
+{
+        flush_sample_queue(session, ops);
+        session->ordered_samples.next_flush = session->ordered_samples.max_timestamp;
+
+        return 0;
+}
+
 static void __queue_sample_end(struct sample_queue *new, struct list_head *head)
 {
         struct sample_queue *iter;
@@ -456,17 +520,12 @@ static void __queue_sample_event(struct sample_queue *new,
 }
 
 static int queue_sample_event(event_t *event, struct sample_data *data,
-                              struct perf_session *s,
-                              struct perf_event_ops *ops)
+                              struct perf_session *s)
 {
         u64 timestamp = data->time;
         struct sample_queue *new;
-        u64 flush_limit;
 
 
-        if (s->ordered_samples.flush_limit == ULLONG_MAX)
-                s->ordered_samples.flush_limit = timestamp + FLUSH_PERIOD;
-
         if (timestamp < s->ordered_samples.last_flush) {
                 printf("Warning: Timestamp below last timeslice flush\n");
                 return -EINVAL;
@@ -489,23 +548,8 @@ static int queue_sample_event(event_t *event, struct sample_data *data,
         __queue_sample_event(new, s);
         s->ordered_samples.last_inserted = new;
 
-        /*
-         * We want to have a slice of events covering 2 * FLUSH_PERIOD
-         * If FLUSH_PERIOD is big enough, it ensures every events that occured
-         * in the first half of the timeslice have all been buffered and there
-         * are none remaining (we need that because of the weakly ordered
-         * event recording we have). Then once we reach the 2 * FLUSH_PERIOD
-         * timeslice, we flush the first half to be gentle with the memory
-         * (the second half can still get new events in the middle, so wait
-         * another period to flush it)
-         */
-        flush_limit = s->ordered_samples.flush_limit;
-
-        if (new->timestamp > flush_limit &&
-                new->timestamp - flush_limit > FLUSH_PERIOD) {
-                s->ordered_samples.flush_limit += FLUSH_PERIOD;
-                flush_sample_queue(s, ops);
-        }
+        if (new->timestamp > s->ordered_samples.max_timestamp)
+                s->ordered_samples.max_timestamp = new->timestamp;
 
         return 0;
 }
@@ -521,7 +565,7 @@ static int perf_session__process_sample(event_t *event, struct perf_session *s,
         bzero(&data, sizeof(struct sample_data));
         event__parse_sample(event, s->sample_type, &data);
 
-        queue_sample_event(event, &data, s, ops);
+        queue_sample_event(event, &data, s);
 
         return 0;
 }
@@ -573,6 +617,8 @@ static int perf_session__process_event(struct perf_session *self,
                 return ops->tracing_data(event, self);
         case PERF_RECORD_HEADER_BUILD_ID:
                 return ops->build_id(event, self);
+        case PERF_RECORD_FINISHED_ROUND:
+                return ops->finished_round(event, self, ops);
         default:
                 self->unknown_events++;
                 return -1;
@@ -651,15 +697,18 @@ more:
         p = &event;
         p += sizeof(struct perf_event_header);
 
-        err = do_read(self->fd, p, size - sizeof(struct perf_event_header));
-        if (err <= 0) {
-                if (err == 0) {
-                        pr_err("unexpected end of event stream\n");
-                        goto done;
-                }
+        if (size - sizeof(struct perf_event_header)) {
+                err = do_read(self->fd, p,
+                              size - sizeof(struct perf_event_header));
+                if (err <= 0) {
+                        if (err == 0) {
+                                pr_err("unexpected end of event stream\n");
+                                goto done;
+                        }
 
-                pr_err("failed to read event data\n");
-                goto out_err;
+                        pr_err("failed to read event data\n");
+                        goto out_err;
+                }
         }
 
         if (size == 0 ||
@@ -787,7 +836,7 @@ more:
 done:
         err = 0;
         /* do the final flush for ordered samples */
-        self->ordered_samples.flush_limit = ULLONG_MAX;
+        self->ordered_samples.next_flush = ULLONG_MAX;
         flush_sample_queue(self, ops);
 out_err:
         ui_progress__delete(progress);