Log Message:
Update to 20110223. Changelog is in Japanese, but author says:

Many bugs are fixed. Especially, a memory leak in queuing.
And it have new experimental multi-threaded mode.
(QueueDepth with -m1 command line option)

In this mode, it improves I/O delay such as small random R/W.
It is also intended to use Quad or more core CPU and 10Gbps link.