Re: [PATCH RFC 0/2] Packed ring for vhost
- Date: Wed, 14 Feb 2018 04:47:34 +0200
- From: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
- Subject: Re: [PATCH RFC 0/2] Packed ring for vhost
On Wed, Feb 14, 2018 at 10:37:07AM +0800, Jason Wang wrote:
> Hi all:
> This RFC implement a subset of packed ring which was described at
> . The code were tested with pmd implement by Jens at
> http://dpdk.org/ml/archives/dev/2018-January/089417.html. Minor
> change was needed for pmd codes to kick virtqueue since it assumes a
> busy polling backend.
> Test were done between localhost and guest. Testpmd (rxonly) in guest
> reports 2.4Mpps. Testpmd (txonly) repots about 2.1Mpps.
How does this compare with the split ring design?
> It's not a complete implemention, here's what were missed:
> - Device Area
> - Driver Area
> - Descriptor indirection
> - Zerocopy may not be functional
> - Migration path is not tested
> - Vhost devices except for net
> - vIOMMU can not work (mainly because the metadata prefetch is not
> - See FIXME/TODO in the codes for more details
> - No batching or other optimizations were implemented
ioeventfd for PIO/mmio/s390.
> For a quick prototype, this series open code the tracking of warp
> counter and descriptor index at net device. This will be addressed in
> the future by:
> - Move get_rx_bufs() from net.c to vhost.c
> - Let vhost_get_vq_desc() returns vring_used_elem instad of head id
> With the above, we can hide the internal (at least part of) vring
> layout from specific device.
> Please review.
> Jason Wang (2):
> virtio: introduce packed ring defines
> vhost: packed ring support
> drivers/vhost/net.c | 14 +-
> drivers/vhost/vhost.c | 351 ++++++++++++++++++++++++++++++++++---
> drivers/vhost/vhost.h | 6 +-
> include/uapi/linux/virtio_config.h | 9 +
> include/uapi/linux/virtio_ring.h | 17 ++
> 5 files changed, 369 insertions(+), 28 deletions(-)