On Nov 18, 2013 7:05 AM, "Stefan Hajnoczi" <stefa...@gmail.com> wrote: > > On Mon, Nov 18, 2013 at 02:52:53PM +1000, Dave Airlie wrote: > > So after talking to a few people at kvm forum I think the GPU code > > should probably use the dataplane stuff from the outset, > > > > The main advantages I think this gives me is being able to dequeue > > objects from the vq from a thread and send irq vectors from there as > > well. > > > > Though since it appears the dataplane stuff is kvm specific (at least > > the irq handling), I was wondering how I should deal with fallbacks > > for non-kvm operation, and quite how much falling back I need to do. > > > > Can I still use the dataplane/vring code from the normal bottom half > > handlers or do I have to write separate code for both situations. > > As of today, there are still two vring implementations in > hw/virtio/virtio.c and hw/virtio/dataplane/vring.c. This means it isn't > clean and easy to integrate into a new device yet. Existing dataplane > devices basically take advantage of the fact that the non-dataplane > version sets up the device before I/O.
I think we also need some form of mdroth's GContext prior to introducing more dataplane devices. Sticking every device in a seperate thread with no way to control who is where can actually hurt performance. I think we really need to have a M-N device thread model too. Regards, Anthony Liguori > > Paolo can give you details on the latest thread-safe memory API stuff > and whether it's already usable for virtio. > > Regarding irqfd, we could emulate it in TCG using an EventNotifier > (eventfd). At that point I think it's no longer kvm-specific. > > Stefan >
