Re: [PATCH net-next v2 6/9] xsk: add direct xmit in batch function

[Stanislav Fomichev <stfomichev@gmail.com>]

On 08/25, Jason Xing wrote:
> From: Jason Xing <kernelxing@tencent.com>
> 
> Add batch xmit logic.
> 
> Only grabbing the lock and disable bottom half once and sent all
> the aggregated packets in one loop.
> 
> Since previous patch puts descriptors in xs->skb_cache in a reversed
> order, this patch sends each skb out from start to end when 'start' is
> not smaller than 'end'.
> 
> Signed-off-by: Jason Xing <kernelxing@tencent.com>
> ---
>  include/linux/netdevice.h |  3 +++
>  net/core/dev.c            | 19 +++++++++++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 5e5de4b0a433..8e2688e3f2e4 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -3352,6 +3352,9 @@ u16 dev_pick_tx_zero(struct net_device *dev, struct sk_buff *skb,
>  
>  int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev);
>  int __dev_direct_xmit(struct sk_buff *skb, u16 queue_id);
> +int xsk_direct_xmit_batch(struct sk_buff **skbs, struct net_device *dev,
> +			  struct netdev_queue *txq, int *cur,
> +			  int start, int end);
>  
>  static inline int dev_queue_xmit(struct sk_buff *skb)
>  {
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 68dc47d7e700..a5a6b9a199e9 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -4742,6 +4742,25 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
>  }
>  EXPORT_SYMBOL(__dev_queue_xmit);
>  
> +int xsk_direct_xmit_batch(struct sk_buff **skbs, struct net_device *dev,
> +			  struct netdev_queue *txq, int *cur,
> +			  int start, int end)
> +{
> +	int ret = NETDEV_TX_BUSY;
> +
> +	local_bh_disable();
> +	HARD_TX_LOCK(dev, txq, smp_processor_id());
> +	for (*cur = start; *cur >= end; (*cur)--) {

skbs support chaining (via list member), any reason not to use that for
batching purposes?