[dpdk-dev] i40e and RSS woes

Zhang, Helin helin.zhang at intel.com
Thu Mar 5 06:56:27 CET 2015


Hi Gleb

Sorry for late! I am struggling on my tasks for the following DPDK release these days.

> -----Original Message-----
> From: Gleb Natapov [mailto:gleb at cloudius-systems.com]
> Sent: Monday, March 2, 2015 8:56 PM
> To: dev at dpdk.org
> Cc: Zhang, Helin
> Subject: Re: i40e and RSS woes
> 
> Ping.
> 
> On Thu, Feb 19, 2015 at 04:50:10PM +0200, Gleb Natapov wrote:
> > CCing i40e driver author in a hope to get an answer.
> >
> > On Mon, Feb 16, 2015 at 03:36:54PM +0200, Gleb Natapov wrote:
> > > I have an application that works reasonably well with ixgbe driver,
> > > but when I try to use it with i40e I encounter various RSS related issues.
> > >
> > > First one is that for some reason i40e, when it builds default reta
> > > table, round down number of queues to power of two. Why is this? If
It seems because of i40e queue configuration. We will check it more and see
if it can be changed or improved later.

> > > I configure reta by my own using all of the queues everything seams
> > > to be working. To add insult to injury I do not get any errors
> > > during configuration some queues just do not receive any traffic.
> > >
> > > The second problem is that for some reason i40e does not use 40 byte
> > > toeplitz hash key like any other driver, but it expects the key to
> > > be 52 bytes. And it would have being fine (if we ignore the fact
> > > that it contradicts MS spec), but how my high level code suppose to know
> that?
Actually a rss_key_len was introduced in struct rte_eth_rss_conf recently. So the
length should be indicated clearly. But I found the annotations of that structure
should have been reworked. I will try to rework it with clear descriptions.

> > > And again, device configuration does not fail when wrong key length
> > > is provided, it just uses some other key. Guys this kind of error
> > > handling is completely unacceptable.
If less length of key is provided, it will not be used at all, the default key will be used.
So there is no issue as you said. But we need to add more clear description for the
structure of rte_eth_rss_conf.

Thank you very much for the good comments!

Regards,
Helin

> > >
> > > The last one is more of a question. Why interface to change RSS hash
> > > function (XOR or toeplitz) is part of a filter configuration and not
> > > rss config?
> > >
> > > --
> > > 			Gleb.
> >
> > --
> > 			Gleb.
> 
> --
> 			Gleb.


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