On Mon, Jul 16, 2018 at 11:28:03AM +0800, Jason Wang wrote:
Hi all:Well the question then is why we should bother merging this
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.
if this doesn't give a performance gain.
Do you see
a gain in CPU utilization maybe?
If not - let's wait for that TCP benchmark result?
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(-)
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2.7.4