- There is now a default 1/4 of a second scheduled delay between delayed

fsync()'s, it can be configured by the max-ack-delay configuration
  parameter.  [ISC-Bugs #17679]

server/stables.c

@@ -240,6 +240,7 @@ static struct option server_options[] = {
 	{ "limit-addrs-per-ia", "L",		&server_universe,  56, 1 },
 	{ "limit-prefs-per-ia", "L",		&server_universe,  57, 1 },
 	{ "delayed-ack", "S",			&server_universe,  58, 1 },
+	{ "max-ack-delay", "L",			&server_universe,  59, 1 },
 	{ NULL, NULL, NULL, 0, 0 }
 };