perf data: Enable stream flush within processing

For big data files the size of data allocated for stream instance could
get really high. It's needed to flush the data out of the stream once in
a while.

Unfortunately there's no size indication in the stream object, so we
govern the flush based on the number of stored events. Current flush
limit is set ot 100000 events.
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jeremie Galarneau <jgalar@efficios.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1429372220-6406-4-git-send-email-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/data-convert-bt.c

@@ -43,6 +43,7 @@ struct evsel_priv {
 struct ctf_stream {
 	struct bt_ctf_stream *stream;
 	int cpu;
+	u32 count;
 };
 
 struct ctf_writer {
@@ -392,7 +393,10 @@ static int ctf_stream__flush(struct ctf_stream *cs)
 		if (err)
 			pr_err("CTF stream %d flush failed\n", cs->cpu);
 
-		pr("Flush stream for cpu %d\n", cs->cpu);
+		pr("Flush stream for cpu %d (%u samples)\n",
+		   cs->cpu, cs->count);
+
+		cs->count = 0;
 	}
 
 	return err;
@@ -490,6 +494,19 @@ static int get_sample_cpu(struct ctf_writer *cw, struct perf_sample *sample,
 	return cpu;
 }
 
+#define STREAM_FLUSH_COUNT 100000
+
+/*
+ * Currently we have no other way to determine the
+ * time for the stream flush other than keep track
+ * of the number of events and check it against
+ * threshold.
+ */
+static bool is_flush_needed(struct ctf_stream *cs)
+{
+	return cs->count >= STREAM_FLUSH_COUNT;
+}
+
 static int process_sample_event(struct perf_tool *tool,
 				union perf_event *_event __maybe_unused,
 				struct perf_sample *sample,
@@ -535,8 +552,13 @@ static int process_sample_event(struct perf_tool *tool,
 	}
 
 	cs = ctf_stream(cw, get_sample_cpu(cw, sample, evsel));
-	if (cs)
+	if (cs) {
+		if (is_flush_needed(cs))
+			ctf_stream__flush(cs);
+
+		cs->count++;
 		bt_ctf_stream_append_event(cs->stream, event);
+	}
 
 	bt_ctf_event_put(event);
 	return cs ? 0 : -1;