I'm sending this out to get some comments especially on the TX path code. I added support for mergeable rx buffers, out of order processing and indirect. The receive path works well but the TX path sometimes locks up after a random number of packets transmitted, so please review this patch extra careful. This is also why I didn't add any new performance numbers to the cover letter yet.
To support out-of-order processing I used the vq_desc_extra struct to add a .next field and use it as a list for managing descriptors. This seemed to add less complexity to the code than adding a new data structure to use as a list for packed queue descriptors. I also took out the patch for supporting virtio-user as it turned out more complex than expected. I will try to get it working for the next version, but if I don't can we add it in a later pach set (and then probably not in 18.11?] This is a basic implementation of packed virtqueues as specified in the Virtio 1.1 draft. A compiled version of the current draft is available at https://github.com/oasis-tcs/virtio-docs.git (or as .pdf at https://github.com/oasis-tcs/virtio-docs/blob/master/virtio-v1.1-packed-wd10.pdf A packed virtqueue is different from a split virtqueue in that it consists of only a single descriptor ring that replaces available and used ring, index and descriptor pointers. Each descriptor is readable and writable and has a flags field. These flags will mark if a descriptor is available or used. To detect new available descriptors even after the ring has wrapped, device and driver each have a single-bit wrap counter that is flipped from 0 to 1 and vice versa every time the last descriptor in the ring is used/made available. Jens Freimann (8): net/virtio: vring init for packed queues net/virtio: add packed virtqueue defines net/virtio: add packed virtqueue helpers net/virtio: dump packed virtqueue data net/virtio: implement transmit path for packed queues net/virtio: implement receive path for packed queues net/virtio: add virtio send command packed queue support net/virtio: enable packed virtqueues by default drivers/net/virtio/virtio_ethdev.c | 161 +++++++-- drivers/net/virtio/virtio_ethdev.h | 5 + drivers/net/virtio/virtio_pci.h | 8 + drivers/net/virtio/virtio_ring.h | 96 ++++- drivers/net/virtio/virtio_rxtx.c | 544 ++++++++++++++++++++++++++++- drivers/net/virtio/virtqueue.c | 23 ++ drivers/net/virtio/virtqueue.h | 52 ++- 7 files changed, 846 insertions(+), 43 deletions(-) -- 2.17.1
