On 16-09-09 04:44 PM, Tom Herbert wrote: > On Fri, Sep 9, 2016 at 2:29 PM, John Fastabend <john.fastab...@gmail.com> > wrote: >> e1000 supports a single TX queue so it is being shared with the stack >> when XDP runs XDP_TX action. This requires taking the xmit lock to >> ensure we don't corrupt the tx ring. To avoid taking and dropping the >> lock per packet this patch adds a bundling implementation to submit >> a bundle of packets to the xmit routine. >> >> I tested this patch running e1000 in a VM using KVM over a tap >> device using pktgen to generate traffic along with 'ping -f -l 100'. >> > Hi John, > > How does this interact with BQL on e1000? > > Tom >
Let me check if I have the API correct. When we enqueue a packet to be sent we must issue a netdev_sent_queue() call and then on actual transmission issue a netdev_completed_queue(). The patch attached here missed a few things though. But it looks like I just need to call netdev_sent_queue() from the e1000_xmit_raw_frame() routine and then let the tx completion logic kick in which will call netdev_completed_queue() correctly. I'll need to add a check for the queue state as well. So if I do these three things, check __QUEUE_STATE_XOFF before sending netdev_sent_queue() -> on XDP_TX netdev_completed_queue() It should work agree? Now should we do this even when XDP owns the queue? Or is this purely an issue with sharing the queue between XDP and stack. .John