[v10,0/9] implement packed virtqueues

  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.

v9-v10:
 * don't mix index into buffer list and descriptors
 * whitespace and formatting issues
 * remove "VQ:" in dump virtqueue patch
 * add extra packed vring struct to virtqueue and change function
   prototypes and code accordingly
 * move wrap_counters to virtqueue
 * make if-conditions for packed and !packed more clear in
   set_rxtx_funcs()
 * initialize wrap counters in first patch, instead of rx and tx
   implementation patch
 * make virtio-user not supported with packed virtqueues, to
   be fixed in other patch set?

v8-v9:
 * fix virtio_ring_free_chain_packed() to handle descriptors
   correctly in case of out-of-order
 * fix check in virtqueue_xmit_cleanup_packed() to improve performance

v7->v8:
 * move desc_is_used change to correct patch
 * remove trailing newline
 * correct xmit code, flags update and memory barrier
 * move packed desc init to dedicated function, split
   and packed variant


Jens Freimann (9):
  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
  net/virtio-user: disable packed virtqueues when CTRL_VQ enabled

 drivers/net/virtio/virtio_ethdev.c            | 202 +++++--
 drivers/net/virtio/virtio_ethdev.h            |   5 +
 drivers/net/virtio/virtio_pci.h               |   7 +
 drivers/net/virtio/virtio_ring.h              |  64 +-
 drivers/net/virtio/virtio_rxtx.c              | 561 +++++++++++++++++-
 .../net/virtio/virtio_user/virtio_user_dev.c  |   1 +
 drivers/net/virtio/virtqueue.c                |  22 +
 drivers/net/virtio/virtqueue.h                |  69 ++-
 8 files changed, 859 insertions(+), 72 deletions(-)
  

On Fri, Nov 02, 2018 at 10:07:40AM +0100, Jens Freimann wrote:
> 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.

Do you have the performance numbers which can show the
performance improvements in driver and vhost?

Thanks

> 
> v9-v10:
>  * don't mix index into buffer list and descriptors
>  * whitespace and formatting issues
>  * remove "VQ:" in dump virtqueue patch
>  * add extra packed vring struct to virtqueue and change function
>    prototypes and code accordingly
>  * move wrap_counters to virtqueue
>  * make if-conditions for packed and !packed more clear in
>    set_rxtx_funcs()
>  * initialize wrap counters in first patch, instead of rx and tx
>    implementation patch
>  * make virtio-user not supported with packed virtqueues, to
>    be fixed in other patch set?
> 
> v8-v9:
>  * fix virtio_ring_free_chain_packed() to handle descriptors
>    correctly in case of out-of-order
>  * fix check in virtqueue_xmit_cleanup_packed() to improve performance
> 
> v7->v8:
>  * move desc_is_used change to correct patch
>  * remove trailing newline
>  * correct xmit code, flags update and memory barrier
>  * move packed desc init to dedicated function, split
>    and packed variant
> 
> 
> Jens Freimann (9):
>   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
>   net/virtio-user: disable packed virtqueues when CTRL_VQ enabled
> 
>  drivers/net/virtio/virtio_ethdev.c            | 202 +++++--
>  drivers/net/virtio/virtio_ethdev.h            |   5 +
>  drivers/net/virtio/virtio_pci.h               |   7 +
>  drivers/net/virtio/virtio_ring.h              |  64 +-
>  drivers/net/virtio/virtio_rxtx.c              | 561 +++++++++++++++++-
>  .../net/virtio/virtio_user/virtio_user_dev.c  |   1 +
>  drivers/net/virtio/virtqueue.c                |  22 +
>  drivers/net/virtio/virtqueue.h                |  69 ++-
>  8 files changed, 859 insertions(+), 72 deletions(-)
> 
> -- 
> 2.17.1
>