Re: [Qemu-devel] [patch] non-blocking disk IO

[Jens Axboe]

On Tue, Oct 04 2005, Troy Benjegerdes wrote:
> What we want is to be able to have the guest OS request some DMA
> I/O operation, and have qemu be able to use AIO so that the actual disk
> hardware can dump the data directly in the pages the userspace process
> on the guest OS ends up wanting it in, avoiding several expensive memcopy
> and context switch operations.

That should be easy enough to do already, with or without the
nonblocking patch. Just make sure to open the files O_DIRECT and align
the io buffers and lengths. With a 2.6 host, you can usually get away
with 512-b aligment, on 2.4 you may have to ensure 1k/4k alignment.

-- 
Jens Axboe