[PATCH net-next v2 9/9] xsk: support dynamic xmit.more control for batch xmit

[Jason Xing <kerneljasonxing@gmail.com>]

From: Jason Xing <kernelxing@tencent.com>

Only set xmit.more false for the last skb.

In theory, only making xmit.more false for the last packets to be
sent in each round can bring much benefit like avoid triggering too
many irqs.

Compared to the numbers for batch mode, a huge improvement (26%) can
be seen on i40e driver while a slight decrease (10%) on virtio_net.

Suggested-by: Jesper Dangaard Brouer <hawk@kernel.org>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
Considering different implmentation in VM and host, I'm not sure if
we need to create another setsockopt to control this...
---
 net/core/dev.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index a5a6b9a199e9..9d28a3d0ce3b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4751,7 +4751,9 @@ int xsk_direct_xmit_batch(struct sk_buff **skbs, struct net_device *dev,
 	local_bh_disable();
 	HARD_TX_LOCK(dev, txq, smp_processor_id());
 	for (*cur = start; *cur >= end; (*cur)--) {
-		ret = netdev_start_xmit(skbs[*cur], dev, txq, false);
+		bool more = !!(*cur != end);
+
+		ret = netdev_start_xmit(skbs[*cur], dev, txq, more);
 		if (ret != NETDEV_TX_OK)
 			break;
 	}
-- 
2.41.3