[dpdk-dev] [PATCH v7 0/8] implement packed virtqueues
Jens Freimann
jfreimann at redhat.com
Wed Oct 3 15:06:38 CEST 2018
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
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