[PATCH 7/8] perf data: Enable stream flush within processing

Jiri Olsa
2014-12-11T15:13:45Z

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.

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jeremie Galarneau <jgalar@efficios.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/perf/util/data-convert-bt.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
index 4bb769e081a8..3d73e51ee10d 100644
--- a/tools/perf/util/data-convert-bt.c
+++ b/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;
--
1.9.3