We need to open the gap between congestion on/off a little bit, or we
risk burning many cycles continually putting processes on a wait queue
only to wake them up again immediately. This was observed with CFQ at
least, which showed way excessive sys time.

Patch is from Arjan.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>