On Thu, 2007-05-31 at 14:57 +0200, Carsten Otte wrote: > Rusty Russell wrote: > > Example block driver using virtio. > > > > The block driver uses outbufs with sg[0] being the request information > > (struct virtio_blk_outhdr) with the type, sector and inbuf id. For a > > write, the rest of the sg will contain the data to be written. > > > > The first segment of the inbuf is a result code (struct > > virtio_blk_inhdr). For a read, the rest of the sg points to the input > > buffer. > > > > TODO: > > 1) Ordered tag support. > Implementing a do_request function has quite a few disadvantages over > hooking into q->make_request_fn. This way, we have the device plug > (latency), request merging, and I/O scheduling inside the guest.
Now my lack of block-layer knowledge is showing. I would have thought that if we want to do things like ionice(1) to work, we have to do some guest scheduling or pass that information down to the host. > It seems preferable to do that in the host, especially when requests > of multiple guests end up on the same physical media (shared access, > or partitioned). What's the overhead in doing both? Rusty. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ kvm-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kvm-devel
