On Thu, 15 Dec 2011 10:32:56 -0800 Rick Jones <rick.jon...@hp.com> wrote:
> > > More exactly, we call dev_queue_xmit_nit() from dev_hard_start_xmit() > > _before_ giving skb to device driver. > > > > If device driver returns NETDEV_TX_BUSY, and a qdisc was setup on the > > device, packet is requeued. > > > > Later, when queue is allowed to send again packets, packet is > > retransmitted (and traced a second time in dev_queue_xmit_nit()) > > Is this then an unintended consequence bug, or a known feature? > > rick > > > You can see the 'requeues' counter from "tc -s -d qdisc" output : > > > > qdisc mq 0: dev eth2 root > > Sent 29421597369 bytes 20301716 pkt (dropped 0, overlimits 0 requeues 371) > > backlog 0b 0p requeues 371 > > Sure enough: > > $ tc -s -d qdisc > qdisc mq 0: dev eth0 root > Sent 2212158799862 bytes 1938268098 pkt (dropped 0, overlimits 0 > requeues 4975139) > backlog 0b 0p requeues 4975139 > > rick jones Device's work better if the driver proactively manages stop_queue/wake_queue. Old devices used TX_BUSY, but newer devices tend to manage the queue themselves. - This is the tcpdump-workers list. Visit https://cod.sandelman.ca/ to unsubscribe.
