X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=gettime.c;h=2037354d0116a122ffb9b698c55b7b9aacbce86b;hp=15356b1b9227c2b92f7676aae124664647f0e5d1;hb=783a3eb15f143d26eed5fd1c943f238057f3ee52;hpb=5bd9c78ce361e3a924013299c53fd823fba05818

diff --git a/gettime.c b/gettime.c
index 15356b1b..2037354d 100644
--- a/gettime.c
+++ b/gettime.c
@@ -22,6 +22,7 @@ static int last_tv_valid;
 static struct timeval *fio_tv;
 int fio_gtod_offload = 0;
 int fio_gtod_cpu = -1;
+static pthread_t gtod_thread;
 
 enum fio_cs fio_clock_source = CS_GTOD;
 
@@ -276,3 +277,56 @@ void fio_gtod_update(void)
 {
 	gettimeofday(fio_tv, NULL);
 }
+
+static void *gtod_thread_main(void *data)
+{
+	struct fio_mutex *mutex = data;
+
+	fio_mutex_up(mutex);
+
+	/*
+	 * As long as we have jobs around, update the clock. It would be nice
+	 * to have some way of NOT hammering that CPU with gettimeofday(),
+	 * but I'm not sure what to use outside of a simple CPU nop to relax
+	 * it - we don't want to lose precision.
+	 */
+	while (threads) {
+		fio_gtod_update();
+		nop;
+	}
+
+	return NULL;
+}
+
+int fio_start_gtod_thread(void)
+{
+	struct fio_mutex *mutex;
+	pthread_attr_t attr;
+	int ret;
+
+	mutex = fio_mutex_init(0);
+	if (!mutex)
+		return 1;
+
+	pthread_attr_init(&attr);
+	pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN);
+	ret = pthread_create(&gtod_thread, &attr, gtod_thread_main, NULL);
+	pthread_attr_destroy(&attr);
+	if (ret) {
+		log_err("Can't create gtod thread: %s\n", strerror(ret));
+		goto err;
+	}
+
+	ret = pthread_detach(gtod_thread);
+	if (ret) {
+		log_err("Can't detatch gtod thread: %s\n", strerror(ret));
+		goto err;
+	}
+
+	dprint(FD_MUTEX, "wait on startup_mutex\n");
+	fio_mutex_down(mutex);
+	dprint(FD_MUTEX, "done waiting on startup_mutex\n");
+err:
+	fio_mutex_remove(mutex);
+	return ret;
+}