throtl/rc: avoid test timeout caused by scsi_debug delay

When the kernel sets CONFIG_HZ=100, throtl/001 fails on the scsi_debug
device. scsi_debug adds 1 jiffy delay to each I/O which takes 0.01
second. Then 256 I/Os take around 2.56 seconds which is reported as 3
seconds. This makes the test case fail which expects I/Os to complete
within 1 second.

To avoid the unexpected failure, set zero value to the scsi_debug delay
parameter. With this, scsi_debug adds no delay, then the 256 I/Os will
take less than 1 second to complete the I/Os. This behavior will be the
same as null_blk.

Link: #221
Signed-off-by: Changhui Zhong <[email protected]>
Signed-off-by: Shin'ichiro Kawasaki <[email protected]>

Author: zhongchanghui

tests/throtl/rc

@@ -75,7 +75,7 @@ _configure_throtl_blkdev() {
 		fi
 		;;
 	sdebug)
-		args=(dev_size_mb=1024)
+		args=(dev_size_mb=1024 delay=0)
 		if _configure_scsi_debug "${args[@]}"; then
 			THROTL_DEV=${SCSI_DEBUG_DEVICES[0]}
 			return