Re: [PATCH V3 net-next 1/1] hv_netvsc: Use the xmit_more skb flag to optimize signaling the host
From: Eric Dumazet <hidden>
Date: 2015-05-06 18:08:58
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On Wed, 2015-05-06 at 11:20 -0700, K. Y. Srinivasan wrote:
Based on the information given to this driver (via the xmit_more skb flag), we can defer signaling the host if more packets are on the way. This will help make the host more efficient since it can potentially process a larger batch of packets. Implement this optimization.
quoted hunk ↗ jump to hunk
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 5993c7e..4efaa6e 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c@@ -435,6 +435,8 @@ check_size: packet->page_buf = page_buf; packet->q_idx = skb_get_queue_mapping(skb); + if (netif_tx_queue_stopped(netdev_get_tx_queue(net, packet->q_idx))) + packet->xmit_more = false;
Have you tested this condition ever triggers ? It should not. netvsc_start_xmit() should not be called if the queue is stopped. The problem is the following : netvsc_start_xmit() is called with the packet that is going to stop the queue, filling last slot, but with skb->xmit_more = 1; So you need to do something about xmit_more, after calling netif_tx_stop_queue(), not before.