iosched: effect of streaming read on interactivity

[Andrew Morton]

Similarly, start a large streaming read on the test box and see how long it
then takes to pop up an x client running on that box with

	time ssh testbox xterm -e true

2.4.21-4:	45 seconds
2.5.61+hacks:	5 seconds
2.5.61+CFQ:	8 seconds
2.5.61+AS:	9 seconds