Provide a ms based sleep function that uses nanosleep to avoid the inaccuracy of usleep on SMP systems.

miner.h

@@ -426,7 +426,7 @@ struct thr_info {
 extern int thr_info_create(struct thr_info *thr, pthread_attr_t *attr, void *(*start) (void *), void *arg);
 extern void thr_info_cancel(struct thr_info *thr);
 extern void thr_info_freeze(struct thr_info *thr);
-
+extern void nmsleep(unsigned int msecs);
 
 struct string_elist {
 	char *string;

util.c

@@ -687,3 +687,14 @@ void thr_info_cancel(struct thr_info *thr)
 		PTH(thr) = 0L;
 	}
 }
+
+/* Provide a ms based sleep that uses nanosleep to avoid poor usleep accuracy
+ * on SMP machines */
+void nmsleep(unsigned int msecs)
+{
+	struct timespec twait;
+
+	twait.tv_sec = msecs / 1000;
+	twait.tv_nsec = (uint64_t)(msecs * 1000000) - (uint64_t)(twait.tv_sec / 1000000000);
+	nanosleep(&twait, NULL);
+}