On Mon, Aug 10, 2009 at 03:33:59PM -0500, Anthony Liguori wrote: > Michael S. Tsirkin wrote: >>> Normally, the common features are transport features and the devices >>> should have absolutely no knowledge of transport feature (since >>> they're transport dependent). >>> >> >> Good point. But >> >> 1. note that with my patch they don't. They call >> virtio_get_common_features and that's all. >> >> 2. some features may not make sense for some devices. For example, it is >> quite possible that indirect ring entries feature improves performance >> on block but hurts on net, as net has a similar merged buffers feature. >> Someone should try benchmarking with it disabled, and it becomes >> possible with my patch. >> > > I don't necessarily disagree but I think your patch goes about it the > wrong way. > > There ought to be a way to layer qdev properties that achieves this goal > so that when you create a virtio-pci-block device, you have the ability > to turn off indirect sg without virtio-block having to know what that is. I don't understand, sorry. Why do you insist on involving pci here? ring layout has nothing to do with pci, does it? With my patch, virtio-block does not know what indirect sg is. It just does enable/disable. virtio net has device-specific feature that overlaps with indirect entries. So insisting that devices should just ignore transport does not make sense, to me. > For your use-case, I wonder if you're integrating at the wrong level. Forget about that for now. Let's solve the generic problem. > Regards, > > Anthony Liguori _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
