[PATCH net-next V3 0/6] switch to use tx skb array in tun

Michael S. Tsirkin
Thu, 30 Jun 2016 05:37:31 -0000

On Thu, Jun 30, 2016 at 11:52:53AM +0800, Jason Wang
wrote:
> Hi all:
>
> This series tries to switch to use skb array in tun. This is used to
> eliminate the spinlock contention between producer and consumer. The
> conversion was straightforward: just introdce a tx skb array and use
> it instead of sk_receive_queue.
>
> A minor issue is to keep the tx_queue_len behaviour, since tun used to
> use it for the length of sk_receive_queue. This is done through:
>
> - add the ability to resize multiple rings at once to avoid handling
>   partial resize failure for mutiple rings.
> - add the support for zero length ring.
> - introduce a notifier which was triggered when tx_queue_len was
>   changed for a netdev.
> - resize all queues during the tx_queue_len changing.
>
> Tests shows about 15% improvement on guest rx pps:
>
> Before: ~1300000pps
> After : ~1500000pps

Series:

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


> Changes from V2:
> - add multiple rings resizing support for ptr_ring/skb_array
> - add zero length ring support
> - introdce a NETDEV_CHANGE_TX_QUEUE_LEN
> - drop new flags
>
> Changes from V1:
> - switch to use skb array instead of a customized circular buffer
> - add non-blocking support
> - rename .peek to .peek_len
> - drop lockless peeking since test show very minor improvement
>
> Jason Wang (5):
>   ptr_ring: support zero length ring
>   skb_array: minor tweak
>   skb_array: add wrappers for resizing
>   net: introduce NETDEV_CHANGE_TX_QUEUE_LEN
>   tun: switch to use skb array for tx
>
> Michael S. Tsirkin (1):
>   ptr_ring: support resizing multiple queues
>
>  drivers/net/tun.c                | 138
++++++++++++++++++++++++++++++++++++---
>  drivers/vhost/net.c              |  16 ++++-
>  include/linux/net.h              |   1 +
>  include/linux/netdevice.h        |   1 +
>  include/linux/ptr_ring.h         |  77 ++++++++++++++++++----
>  include/linux/skb_array.h        |  13 +++-
>  net/core/net-sysfs.c             |  15 ++++-
>  tools/virtio/ringtest/ptr_ring.c |   5 ++
>  8 files changed, 243 insertions(+), 23 deletions(-)
>
> --
> 2.7.4