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Subject[PATCH 52/53] perf record: Toggle tailsize ring buffer for reading
Date
Toggel tailsize_evt_stopped director after receiving done or switch
output. After this patch it is possible to trigger a dump use SIGUSR2
when something happen.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: He Kuang <hekuang@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
tools/perf/builtin-record.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 6c8905b..6ec0529 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -591,6 +591,26 @@ static void record__init_features(struct record *rec)
}

static void
+record__toggle_tailsize_evsels(struct record *rec, bool stop)
+{
+ struct perf_evsel *pos;
+ struct perf_evlist *evlist = rec->evlist;
+
+ evlist__for_each(evlist, pos) {
+ if (!pos->tailsize)
+ continue;
+ if (!pos->overwrite)
+ continue;
+ if (stop)
+ perf_evsel__disable(pos);
+ else
+ perf_evsel__enable(pos);
+ }
+
+ rec->tailsize_evt_stopped = stop;
+}
+
+static void
record__finish_output(struct record *rec)
{
struct perf_data_file *file = &rec->file;
@@ -925,6 +945,9 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
for (;;) {
unsigned long long hits = rec->samples;

+ if (switch_output_started || done)
+ record__toggle_tailsize_evsels(rec, true);
+
if (record__mmap_read_all(rec) < 0) {
auxtrace_snapshot_disable();
err = -1;
@@ -943,7 +966,20 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
}

if (switch_output_started) {
+ /*
+ * SIGUSR2 raise after or during record__mmap_read_all().
+ * continue to read again.
+ */
+ if (!rec->tailsize_evt_stopped)
+ continue;
+
switch_output_started = 0;
+ /*
+ * Reenable events in tailsize ring buffer after
+ * record__mmap_read_all(): we have collected
+ * data from it.
+ */
+ record__toggle_tailsize_evsels(rec, false);

if (!quiet)
fprintf(stderr, "[ perf record: dump data: Woken up %ld times ]\n",
--
1.8.3.4
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