On Fri, Sep 6, 2013 at 10:51 AM, Wyborny, Carolyn
<[email protected]> wrote:

> Hello Andy,
>
> I work primarily on the igb driver.  Thanks to Emil for helping out with 
> this.  "Upstream" is kernel source from kernel.org.  We provide two 
> equivalent igb drivers, the latest upstream kernel and an out of tree driver 
> located at Source Forge.  The driver that comes with your distribution is 
> based on the upstream version but can be modified by the distribution vendor. 
>  The RSS parameter is configurable at driver load with the out of tree driver 
> only.  This kind of configuration is not allowed upstream.  The upstream 
> version configures RSS as max number of cpu's or max queues, whichever is 
> less by default.  The out of tree default is a single pair of queues.  You 
> can see what is configured by the driver load in this regard by running dmesg.
>
> What are you trying to accomplish and I'll try to help you get there.

Hi Carolyn,

Thanks for your detailed reply. My situation is that I was running the
Oracle Unbreakable Kernel v2 which ships with igb 4.0.17, and contains
all the module paramaters you get from the intel sources. As you
described, this version was starting up with 1 combined Tx/Rx queue
per network port. I then upgraded to 3.8.13 from kernel.org and again
found the behavior you described - I was now finding 8 combined Tx/Rx
queue per network port (the max for the card I believe, but also, the
number of CPUs).

I am not entirely certain that this is what I will want to do, but
initially I was interested in reconfiguring the igb driver to create
queues as it did under the Oracle kernel. This is when I discovered
that the module options I was used to seeing (though not utilizing)
under the Oracle kernel's included igb were not available in the
kernel.org source. I saw that it appeared some things were still
accessible (like coalescing settings) via ethtool, but couldn't find
how to set RSS anywhere, and this is when I started asking questions.

So then is the situation that the module options are pulled out of the
upstream sources for compliance reasons with an aim to have them
available via ethtool, or some other user space tool, but that not all
features available as module options have been ported into user space
tools?

As far as getting where I need to be, if I do decide to use the RSS
feature, I think I'm fine using the igb 5.0.5 build I have. It was
just a little confusing at first trying to determine where the module
options had gone.

Thanks again for this information. It is very helpful.
Andy

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