[dpdk-dev] [PATCH v12 00/10] implement packed virtqueues

Maxime Coquelin maxime.coquelin at redhat.com
Thu Dec 13 17:38:02 CET 2018



On 12/13/18 1:34 PM, 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.
> 
> With this patch set I see performance equal or slightly better (+2-3%) in a PVP
> scenario compared to split virtqueues (v18.11 in host)
> 
> regards,
> Jens
> 
> 
> v11->v12:
>   * add a patch to disable control vq when packed vq is enabled.
>     I have a patch to support this but it needs a bit more work
>     and I think it shouldn't stop this series from being applied
>   * rework mergeable receive buffer code to be more efficient, by
>     batching descriptor refill, similar to what Maxime proposed for
>     split virtqueues
>   * removed unnecessary checks in virtio_recv_mergeable_pkts_packed
>     (Maxime)
>   * Did not merge receive functions as Maxime suggested because it seemed
>     to cause a small performance regression
>   * Move event_flags_shadow from patch 3 to 1 (Maxime)
>   * Did not merge xmit functions and call _split/_packed functions from
>     there because it seemed to cause small performance drop (-0.5%)
>     (Maxime)
> 
> v10-v11:
>   * this version includes some fixes from Tiwei, so I added his
>     Signed-off-by to some of the patches
>   * fix hang with mergable rx buffers (Tiwei)
>   * clean-up code and simplify buffer handling (Tiwei)
>   * rebase to current virtio-next master branch
> 
> 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

Note that the series build is broken until this patch.

>    net/virtio: implement receive path for packed queues
>    net/virtio: add virtio send command packed queue support
>    net/virtio-user: ctrl virtqueue not supported with packed vqs
>    net/virtio: enable packed virtqueues by default
> 
> Yuanhan Liu (1):
>    net/virtio-user: add option to use packed queues
> 
>   drivers/net/virtio/virtio_ethdev.c            | 227 +++++--
>   drivers/net/virtio/virtio_ethdev.h            |   8 +
>   drivers/net/virtio/virtio_pci.h               |   7 +
>   drivers/net/virtio/virtio_ring.h              |  64 +-
>   drivers/net/virtio/virtio_rxtx.c              | 620 +++++++++++++++++-
>   .../net/virtio/virtio_user/virtio_user_dev.c  |  25 +-
>   .../net/virtio/virtio_user/virtio_user_dev.h  |   2 +-
>   drivers/net/virtio/virtio_user_ethdev.c       |  14 +-
>   drivers/net/virtio/virtqueue.c                |  22 +
>   drivers/net/virtio/virtqueue.h                | 122 +++-
>   10 files changed, 1035 insertions(+), 76 deletions(-)
> 


More information about the dev mailing list