perf record: Stop threads in the end of trace streaming

Signal thread to terminate by closing write fd of msg pipe.
Receive THREAD_MSG__READY message as the confirmation of the
thread's termination. Stop threads created for parallel trace
streaming prior their stats processing.

Reviewed-by: Riccardo Mancini <rickyman7@gmail.com>
Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Riccardo Mancini <rickyman7@gmail.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Namhyung Kim <namhyung@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Antonov <alexander.antonov@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/55ef8cc5ec3a96360660d9dc1763573225325f8c.1642440724.git.alexey.v.bayduraev@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 163d261dd293c844b9c3e7d3ba226257016d0cdc..0e65b80927b7447551797be520965954ad225785 100644 (file)
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -114,6 +114,16 @@ struct record_thread {
 
 static __thread struct record_thread *thread;
 
+enum thread_msg {
+       THREAD_MSG__UNDEFINED = 0,
+       THREAD_MSG__READY,
+       THREAD_MSG__MAX,
+};
+
+static const char *thread_msg_tags[THREAD_MSG__MAX] = {
+       "UNDEFINED", "READY"
+};
+
 struct record {
        struct perf_tool        tool;
        struct record_opts      opts;
@@ -1886,6 +1896,24 @@ static void record__uniquify_name(struct record *rec)
        }
 }
 
+static int record__terminate_thread(struct record_thread *thread_data)
+{
+       int err;
+       enum thread_msg ack = THREAD_MSG__UNDEFINED;
+       pid_t tid = thread_data->tid;
+
+       close(thread_data->pipes.msg[1]);
+       thread_data->pipes.msg[1] = -1;
+       err = read(thread_data->pipes.ack[0], &ack, sizeof(ack));
+       if (err > 0)
+               pr_debug2("threads[%d]: sent %s\n", tid, thread_msg_tags[ack]);
+       else
+               pr_warning("threads[%d]: failed to receive termination notification from %d\n",
+                          thread->tid, tid);
+
+       return 0;
+}
+
 static int record__start_threads(struct record *rec)
 {
        struct record_thread *thread_data = rec->thread_data;
@@ -1902,6 +1930,9 @@ static int record__stop_threads(struct record *rec)
        int t;
        struct record_thread *thread_data = rec->thread_data;
 
+       for (t = 1; t < rec->nr_threads; t++)
+               record__terminate_thread(&thread_data[t]);
+
        for (t = 0; t < rec->nr_threads; t++)
                rec->samples += thread_data[t].samples;