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Message-ID: <1463126174-119290-17-git-send-email-wangnan0@huawei.com>
Date: Fri, 13 May 2016 07:56:13 +0000
From: Wang Nan <wangnan0@...wei.com>
To: <acme@...nel.org>
CC: <arnaldo.melo@...il.com>, <linux-kernel@...r.kernel.org>,
Wang Nan <wangnan0@...wei.com>, He Kuang <hekuang@...wei.com>,
"Arnaldo Carvalho de Melo" <acme@...hat.com>,
Jiri Olsa <jolsa@...nel.org>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
Namhyung Kim <namhyung@...nel.org>,
"Zefan Li" <lizefan@...wei.com>, <pi3orama@....com>
Subject: [PATCH 16/17] perf record: Toggle overwrite ring buffer for reading
Reading from a overwrite ring buffer is unrelible.
perf_evlist__channel_toggle_paused() should be called before
reading from them.
Toggel overwrite_evt_paused director after receiving done or switch
output.
Signed-off-by: Wang Nan <wangnan0@...wei.com>
Signed-off-by: He Kuang <hekuang@...wei.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Zefan Li <lizefan@...wei.com>
Cc: pi3orama@....com
---
tools/perf/builtin-record.c | 94 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 92 insertions(+), 2 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index e637ea2..606fcd05 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -42,6 +42,11 @@
#include <sys/mman.h>
#include <asm/bug.h>
+enum overwrite_evt_state {
+ OVERWRITE_EVT_RUNNING,
+ OVERWRITE_EVT_DATA_PENDING,
+ OVERWRITE_EVT_EMPTY,
+};
struct record {
struct perf_tool tool;
@@ -60,6 +65,7 @@ struct record {
bool buildid_all;
bool timestamp_filename;
bool switch_output;
+ enum overwrite_evt_state overwrite_evt_state;
unsigned long long samples;
};
@@ -416,6 +422,7 @@ try_again:
session->evlist = evlist;
perf_session__set_id_hdr_size(session);
+ rec->overwrite_evt_state = OVERWRITE_EVT_RUNNING;
out:
return rc;
}
@@ -496,6 +503,52 @@ static struct perf_event_header finished_round_event = {
.type = PERF_RECORD_FINISHED_ROUND,
};
+static void
+record__toggle_overwrite_evsels(struct record *rec,
+ enum overwrite_evt_state state)
+{
+ struct perf_evlist *evlist = rec->evlist;
+ enum overwrite_evt_state old_state = rec->overwrite_evt_state;
+ enum action {
+ NONE,
+ PAUSE,
+ RESUME,
+ } action = NONE;
+ int ch, nr_channels;
+
+ switch (old_state) {
+ case OVERWRITE_EVT_RUNNING:
+ if (state != OVERWRITE_EVT_RUNNING)
+ action = PAUSE;
+ break;
+ case OVERWRITE_EVT_DATA_PENDING:
+ if (state == OVERWRITE_EVT_RUNNING)
+ action = RESUME;
+ break;
+ case OVERWRITE_EVT_EMPTY:
+ if (state == OVERWRITE_EVT_RUNNING)
+ action = RESUME;
+ if (state == OVERWRITE_EVT_DATA_PENDING)
+ state = OVERWRITE_EVT_EMPTY;
+ break;
+ default:
+ WARN_ONCE(1, "Shouldn't get there\n");
+ }
+
+ rec->overwrite_evt_state = state;
+
+ if (action == NONE)
+ return;
+
+ nr_channels = perf_evlist__channel_nr(evlist);
+ for (ch = 0; ch < nr_channels; ch++) {
+ if (!perf_evlist__channel_check(evlist, ch, RDONLY))
+ continue;
+ perf_evlist__channel_toggle_paused(evlist, ch,
+ action == PAUSE);
+ }
+}
+
static bool record__mmap_should_read(struct record *rec, int idx)
{
int channel = -1;
@@ -504,8 +557,13 @@ static bool record__mmap_should_read(struct record *rec, int idx)
return false;
if (perf_evlist__channel_idx(rec->evlist, &channel, &idx))
return false;
- if (perf_evlist__channel_check(rec->evlist, channel, RDONLY))
- return false;
+ if (perf_evlist__channel_check(rec->evlist, channel, RDONLY)) {
+ if (rec->overwrite_evt_state != OVERWRITE_EVT_DATA_PENDING)
+ return false;
+ if (!perf_evlist__channel_check(rec->evlist, channel, BACKWARD))
+ return false;
+ return true;
+ }
return true;
}
@@ -540,6 +598,8 @@ static int record__mmap_read_all(struct record *rec)
if (bytes_written != rec->bytes_written)
rc = record__write(rec, &finished_round_event, sizeof(finished_round_event));
+ if (rec->overwrite_evt_state == OVERWRITE_EVT_DATA_PENDING)
+ record__toggle_overwrite_evsels(rec, OVERWRITE_EVT_EMPTY);
out:
return rc;
}
@@ -917,6 +977,17 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
for (;;) {
unsigned long long hits = rec->samples;
+ /*
+ * rec->overwrite_evt_state is possible to be
+ * OVERWRITE_EVT_EMPTY here: when done == true and
+ * hits != rec->samples after previous reading.
+ *
+ * record__toggle_overwrite_evsels ensure we never
+ * convert OVERWRITE_EVT_EMPTY to OVERWRITE_EVT_DATA_PENDING.
+ */
+ if (trigger_is_hit(&switch_output_trigger) || done || draining)
+ record__toggle_overwrite_evsels(rec, OVERWRITE_EVT_DATA_PENDING);
+
if (record__mmap_read_all(rec) < 0) {
trigger_error(&auxtrace_snapshot_trigger);
trigger_error(&switch_output_trigger);
@@ -936,8 +1007,27 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
}
if (trigger_is_hit(&switch_output_trigger)) {
+ /*
+ * If switch_output_trigger is hit, the data in
+ * overwritable ring buffer should have been collected,
+ * so overwrite_evt_state should be set to
+ * OVERWRITE_EVT_EMPTY.
+ *
+ * If SIGUSR2 raise after or during record__mmap_read_all(),
+ * record__mmap_read_all() didn't collect data from
+ * overwritable ring buffer. Read again.
+ */
+ if (rec->overwrite_evt_state == OVERWRITE_EVT_RUNNING)
+ continue;
trigger_ready(&switch_output_trigger);
+ /*
+ * Reenable events in overwrite ring buffer after
+ * record__mmap_read_all(): we should have collected
+ * data from it.
+ */
+ record__toggle_overwrite_evsels(rec, OVERWRITE_EVT_RUNNING);
+
if (!quiet)
fprintf(stderr, "[ perf record: dump data: Woken up %ld times ]\n",
waking);
--
1.8.3.4
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