Re: [PATCH net-next] fq_codel: report congestion notification at enqueue time

Eric Dumazet
2012-06-29T04:18:59Z

On Thu, 2012-06-28 at 16:52 -0700, Nandita Dukkipati wrote:
> As you know I really like this idea. My main concern is that the same
> packet could cause TCP to reduce cwnd twice within an RTT - first on
> enqueue and then if this packet is ECN marked on dequeue. I don't
> think this is the desired behavior. Can we avoid it?

I'll work on this.

In my experiences, I found that no drops (or ECN marks) were done at
dequeue time once one NET_XMIT_CN was returned, but its certainly
possible if other flows compete with this one.

Strangely, SFQ has the same behavior and nobody complained yet ;)

Thanks