Re: TX Multiqueue?

On 9/23/07, Kip Macy <kip.macy@xxxxxxxxx> wrote:
On 9/23/07, Darren Reed <darrenr@xxxxxxxxxxx> wrote:
Kip Macy wrote:
My ethng branch supports multiple rx and tx queues.

-Kip


What are your plans for how we use/manage/interact with the mutiple
rx/tx queues?

The rx hardware queue is determined by the hardware. Different
hardware allows for different policies. I just use the stock rss_hash
of a crc32 of the 4-tuple in cxgb. I've added a field to the pkthdr
which cxgb uses the least significant bits of to determine which
outbound queue to use. Its up to the upper layers to determine how to
set those bits. One of the changes that is required to take advantaged
of this is moving the queues into the driver. I've added a new
if_start function to ifnet to take advantage of this. I also have a
normal if_start function for backward compatibility.

Yes, the queues in Oplin and Zoar are also a hardware feature, not
just some software infrastructure. There are a number of different
ways that it can be configured. I did not have some settled notion
of how things should be managed but I would rather not have it
be something done under the covers in the driver, a configurable
stack option seems better to me. This needs to be done right or
it will just be a hack, I don't know who the right parties are, it should
not be just a one-person decision, those with a stake in this sort
of thing should all be involved.

Cheers,

Jack
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