[Intel-wired-lan] [PATCH] igb: Enable RSS for i211 adapter

[Alexander Duyck]

On Fri, Dec 18, 2015 at 1:49 AM, Tal Abudi <talabudi at gmail.com> wrote:
> The I211 supports only 2 queues according to the datasheet.
> Is there a real difference between E1000_MRQC_ENABLE_RSS_4Q and
> E1000_MRQC_ENABLE_RSS_8Q ?

I suspect is is just naming.  This should probably be updated to
remove the _XQ entirely.  On 82575 we only supported 4 queues for RSS,
on 82576 it was as much as 16 if I recall correctly.  For 82580, i350,
and i211 I think it is 8, and on i211 it is only 2 but the datasheet
calls it out as RSS_4Q which I believe refers back to the original
82575 documentation.  Since the number varies all over the place we
probably should go through and rename the define.

> The number of the rss is set inside the adapter and the netdevice's dev.
> And we can see in igb_init_queue_configuration() that max_rss_queues =
> IGB_MAX_RX_QUEUES_I211 (2).

Right we only support 2 queues on this hardware, but the datasheet is
calling out 4Q as that is what it was defined in the first iteration
of this driver for the 82575 hardware.  We should have probably
updated this when 82576 was introduced but it looks like the define
was never renamed.

> I tested 5.3.2 with this patch on a 2 core system and packets distributed
> evenly among queues.

Thanks for testing this.  At least we now know that was the issue.

> This is most defective a bug, right ?

This is a bug.  We just need to leave it to the Intel guys to sort out
as I think there may need to be a rename or move of some of the
defines in their initialization code.

- Alex