On Thu, Apr 17, 2008 at 02:26:50PM -0500, Anthony Liguori wrote:
Posix AIO, especially as used by QEMU, is not very efficient for disk IO.
This patch introduces an AIO abstract to allow multiple AIO implements to be
used. We can't simply replace posix-aio by linux-aio because linux-aio only
works on some filesystems and only with files opened with O_DIRECT.
This patch adds a command line option (-aio) to select the AIO implementation
to be used. It avoids code motion to allow for easy review. The next patch
separates out the posix-aio implementation.
This is not a very pleasant user experiance. They can not & should not be
expected to figure out which AIO impl works with their particular filesystem.
If the linux-aio impl doesn't work in some cases, then the code should detect
these and automatically fallback to posix-aio. The user should not have to
use a -aio flag to make it work.