Subject: Re: [PATCH] NET: Multiqueue network device support.

From: Patrick McHardy <[email-masked]>
Date: Mon, 11 Jun 2007 20:05:38 +0200

Waskiewicz Jr, Peter P wrote:
>>I think we can reuse skb->priority. Assuming only real 
>>hardware devices use multiqueue support, there should be no user of
>>skb->priority after egress qdisc classification. The only reason
>>to preserve it in the qdisc layer is for software devices.
> 
> 
> That would be oustanding.
> 
> 
>>Grepping through drivers/net shows a few users, bot most seem 
>>to be using it on the RX path and some use it to store internal data.
> 
> 
> Thank you for hunting this down.  I will test on my little environment
> here to see if I run into any issues.

I think grepping will help more than testing :)

The only issue I can see is that packets going to a multiqueue device
that doesn't have a multiqueue aware qdisc attached will get a random
value. So you would have to conditionally reset it before ->enqueue.

Another question is what to do about other hard_start_xmit callers.
Independant of which field is used, should the classification that
may have happend on a different device be retained (TC actions again)?