[PATCH net-next V2 0/8] Packed virtqueue support for vhost

Jason Wang
Mon, 16 Jul 2018 03:28:03 -0000

Hi all:

This series implements packed virtqueues. The code were tested with
Tiwei's guest driver series at https://patchwork.ozlabs.org/cover/942297/


Pktgen test for both RX and TX does not show obvious difference with
split virtqueues. The main bottleneck is the guest Linux driver, since
it can not stress vhost for a 100% CPU utilization. A full TCP
benchmark is ongoing. Will test virtio-net pmd as well when it was
ready.

Notes:
- This version depends on Tiwei's series at
https://patchwork.ozlabs.org/cover/942297/

This version were tested with:

- Zerocopy (Out of Order) support
- vIOMMU support
- mergeable buffer on/off
- busy polling on/off
- vsock (nc-vsock)

Changes from V1:
- drop uapi patch and use Tiwei's
- split the enablement of packed virtqueue into a separate patch

Changes from RFC V5:

- save unnecessary barriers during vhost_add_used_packed_n()
- more compact math for event idx
- fix failure of SET_VRING_BASE when avail_wrap_counter is true
- fix not copy avail_wrap_counter during GET_VRING_BASE
- introduce SET_VRING_USED_BASE/GET_VRING_USED_BASE for syncing last_used_idx
- rename used_wrap_counter to last_used_wrap_counter
- rebase to net-next

Changes from RFC V4:

- fix signalled_used index recording
- track avail index correctly
- various minor fixes

Changes from RFC V3:

- Fix math on event idx checking
- Sync last avail wrap counter through GET/SET_VRING_BASE
- remove desc_event prefix in the driver/device structure

Changes from RFC V2:

- do not use & in checking desc_event_flags
- off should be most significant bit
- remove the workaround of mergeable buffer for dpdk prototype
- id should be in the last descriptor in the chain
- keep _F_WRITE for write descriptor when adding used
- device flags updating should use ADDR_USED type
- return error on unexpected unavail descriptor in a chain
- return false in vhost_ve_avail_empty is descriptor is available
- track last seen avail_wrap_counter
- correctly examine available descriptor in get_indirect_packed()
- vhost_idx_diff should return u16 instead of bool

Changes from RFC V1:

- Refactor vhost used elem code to avoid open coding on used elem
- Event suppression support (compile test only).
- Indirect descriptor support (compile test only).
- Zerocopy support.
- vIOMMU support.
- SCSI/VSOCK support (compile test only).
- Fix several bugs

Jason Wang (8):
  vhost: move get_rx_bufs to vhost.c
  vhost: hide used ring layout from device
  vhost: do not use vring_used_elem
  vhost_net: do not explicitly manipulate vhost_used_elem
  vhost: vhost_put_user() can accept metadata type
  vhost: packed ring support
  vhost: event suppression for packed ring
  vhost: enable packed virtqueues

 drivers/vhost/net.c        | 143 ++-----
 drivers/vhost/scsi.c       |  62 +--
 drivers/vhost/vhost.c      | 994 ++++++++++++++++++++++++++++++++++++++++-----
 drivers/vhost/vhost.h      |  55 ++-
 drivers/vhost/vsock.c      |  42 +-
 include/uapi/linux/vhost.h |   7 +
 6 files changed, 1035 insertions(+), 268 deletions(-)

--
2.7.4