Re: [PATCH v7 16/46] virtio_blk: v1.0 support

Michael S. Tsirkin
2014-12-01T13:47:44Z

On Mon, Dec 01, 2014 at 02:00:04PM +0100, Cornelia Huck wrote:
> On Mon, 1 Dec 2014 14:51:26 +0200
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
>
> > On Mon, Dec 01, 2014 at 01:40:36PM +0100, Cornelia Huck wrote:
> > > On Mon, 1 Dec 2014 14:34:55 +0200
> > > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > >
> > > > On Mon, Dec 01, 2014 at 01:02:58PM +0100, Cornelia Huck wrote:
> > > > > On Mon, 1 Dec 2014 13:46:45 +0200
> > > > > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > > > >
> > > > > > On Mon, Dec 01, 2014 at 12:33:15PM +0100, Cornelia Huck wrote:
> > > > > > > On Mon, 1 Dec 2014 11:26:58 +0200
> > > > > > > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > > > > > >
> > > > > > > > For some places on data path, it might be worth it
> > > > > > > > to cache the correct value e.g. as part of device
> > > > > > > > structure. This replaces a branch with a memory load,
> > > > > > > > so the gain would have to be measured, best done
> > > > > > > > separately?
> > > > > > >
> > > > > > > I think we'll want to do some measuring once the basic structure is
> > > > > > > in place anyway.
> > > > > >
> > > > > > What's meant by in place here?
> > > > >
> > > > > That this patchset is ready :)
> > > >
> > > > Also it's ready to the level where benchmarking is possible, right? I
> > > > don't think you should wait until we finish polishing up commit
> > > > messages.
> > >
> > > My point is that I haven't even found time yet to test this
> > > thouroughly :(
> >
> > If my experience shows anything, it's unlikely we'll get appropriate
> > testing without code being upstream first.
> > That's why I pushed on with sparse tagging btw.
> > This way we can be reasonably sure we didn't miss some path.
>
> I know that I'm likely the only one to test ccw (unless I manage to get
> some other also-busy people to try this out).
>
> What's the status of virtio-pci, btw? Can people actually test this
> sanely?

Sure, I'm testing that it's not broken by these patches.
Others can do so, too.

Once ccw is done on host and guest (will be complete after I
send v8), it will be easier to add virtio 1.0 for more transports.

OTOH if we require that everything is ready and perfect before merging
anything we'll never get anywhere.

--
MST