K 10
svn:author
V 3
mav
K 8
svn:date
V 27
2015-03-15T14:57:11.250207Z
K 7
svn:log
V 630
Rewrite virtio block device driver to work asynchronously and use the block
I/O interface.

Asynchronous operation, based on r280026 change, allows to not block virtual
CPU during I/O processing, that on slow/busy storage can take seconds.
Use of recently improved block I/O interface allows to process multiple
requests same time, that improves random I/O performance on wide storages.

Benchmarks of virtual disk, backed by ZVOL on RAID10 pool of 4 HDDs, show
~3.5 times random read performance improvements, while no degradation on
linear I/O.  Guest CPU usage during test dropped from 100% to almost zero.

MFC after:	2 weeks

END