On Sun, Oct 29, 2017 at 01:52:25PM +0100, Jens Freimann wrote: > Ilya: - you might have more completions than descriptors available > - partial descriptor chains are a problem for hardware because you might have > to read a bunch of conscriptors twice - how would you do deal with a big > buffer that cointains a large number of > small packets with respect to completions? > - is one bit for completion enough? right now it means descriptor was actually > used. how to we signal when it was completed?
I am not sure I understand the difference. Under virtio, driver makes a descriptor available, then device reads/writes memory depending on descriptor type, then marks it as used. What does completed mean? > - concerned about not being able to do scatter/gatter with the ring layout. > Network drivers heavily using indirect buffers. - for a hardware > implementation a completion ring is a very convenient form for > some use cases, so we want an efficient implementation for them. If we had an > inline descriptor then a completion ring is just a normal ring and we won't > need another ring type. > - doesn't like the fact that we need to do a linear scan to find the length of > a descriptor chain. It would be nice if we could have the length of the chain > in the first descriptor (i.e. the number of chained descriptors, not the > number > of posted descriptors which can be deduced from the id field) Not responding to rest of points since I don't understand the basic assumption above yet. -- MST _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
