Re: [PATCH net-next V5 0/9] vhost_net rx batch dequeuing

Michael S. Tsirkin
2017-05-17T21:00:05Z

On Wed, May 17, 2017 at 12:14:36PM +0800, Jason Wang wrote:
> This series tries to implement rx batching for vhost-net. This is done
> by batching the dequeuing from skb_array which was exported by
> underlayer socket and pass the sbk back through msg_control to finish
> userspace copying. This is also the requirement for more batching
> implemention on rx path.
>
> Tests shows at most 7.56% improvment bon rx pps on top of batch
> zeroing and no obvious changes for TCP_STREAM/TCP_RR result.
>
> Please review.
>
> Thanks

A surprisingly large gain for such as simple change. It would be nice
to understand better why this helps - in particular, does the optimal
batch size change if ring is bigger or smaller? But let's merge it
meanwhile.

Series:

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> Changes from V4:
> - drop batch zeroing patch
> - renew the performance numbers
> - move skb pointer array out of vhost_net structure
>
> Changes from V3:
> - add batch zeroing patch to fix the build warnings
>
> Changes from V2:
> - rebase to net-next HEAD
> - use unconsume helpers to put skb back on releasing
> - introduce and use vhost_net internal buffer helpers
> - renew performance numbers on top of batch zeroing
>
> Changes from V1:
> - switch to use for() in __ptr_ring_consume_batched()
> - rename peek_head_len_batched() to fetch_skbs()
> - use skb_array_consume_batched() instead of
> skb_array_consume_batched_bh() since no consumer run in bh
> - drop the lockless peeking patch since skb_array could be resized, so
> it's not safe to call lockless one
>
> Jason Wang (8):
> skb_array: introduce skb_array_unconsume
> ptr_ring: introduce batch dequeuing
> skb_array: introduce batch dequeuing
> tun: export skb_array
> tap: export skb_array
> tun: support receiving skb through msg_control
> tap: support receiving skb from msg_control
> vhost_net: try batch dequing from skb array
>
> Michael S. Tsirkin (1):
> ptr_ring: add ptr_ring_unconsume
>
> drivers/net/tap.c | 25 +++++++--
> drivers/net/tun.c | 31 ++++++++---
> drivers/vhost/net.c | 128 +++++++++++++++++++++++++++++++++++++++++++---
> include/linux/if_tap.h | 5 ++
> include/linux/if_tun.h | 5 ++
> include/linux/ptr_ring.h | 120 +++++++++++++++++++++++++++++++++++++++++++
> include/linux/skb_array.h | 31 +++++++++++
> 7 files changed, 327 insertions(+), 18 deletions(-)
>
> --
> 2.7.4