Subject: RE: [PATCH] IPROUTE: Modify tc for new PRIO multiqueue behavior

From: jamal <[email-masked]>
Date: Tue, 08 May 2007 09:28:37 -0400

On Tue, 2007-08-05 at 11:45 +0200, Johannes Berg wrote:
..

Sorry, I missed a lot of the discussions; I am busyed out and will try
to catchup later tonight. I have quickly scanned the emails and
I will respond backwards (typically the most effective
way to catchup with a thread).

As a summary, I am not against the concept of addressing per-ring flow
control. 
Having said that, i fully understand where DaveM and Stephen are coming
from. Making such huge changes to a critical region to support uncommon
hardware doesnt abide to the "optimize for the common" paradigm. That is
also the basis of my arguement all along. I also agree it is quiet
fscked an approach to have the virtual flow control. I think it is
driven by some marketing people and i dont really think there is a
science behind it. Switched (External) PCI-E which is supposed to be
really cheap and hit the market RSN has per-virtual queue flow control,
so that maybe where that came from. In any case, that is a digression. 
Peter, can we meet the goals you strive for and stick to the "optimize
for the common"? How willing are you to change directions to achieve
those goals?

> On Tue, 2007-05-08 at 17:33 +0800, Zhu Yi wrote:
> 
> > Jamal, as you said, the wireless subsystem uses an interim workaround
> > (the extra netdev approach) to achieve hardware packets scheduling. But
> > with Peter's patch, the wireless stack doesn't need the workaround
> > anymore. This is the actual fix.
> 

I dont believe wireless needs anything other than the simple approach i
described. The fact that there an occasional low prio packet may endup
going out first before a high prio due to the contention is
non-affecting to the overall results.

> Actually, we still need multiple devices for virtual devices? Or which
> multiple devices are you talking about here?
> 

Those virtual devices you have right now. They are a hack that needs to
go at some point.

cheers,
jamal