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

Fujinaka, Todd todd.fujinaka at intel.com
Fri Dec 18 15:48:41 UTC 2015


Good idea on the renaming Alex. I'll put that on my list.

Todd Fujinaka
Software Application Engineer
Networking Division (ND)
Intel Corporation
todd.fujinaka at intel.com
(503) 712-4565

-----Original Message-----
From: Alexander Duyck [mailto:alexander.duyck at gmail.com] 
Sent: Friday, December 18, 2015 7:14 AM
To: Tal Abudi
Cc: Fujinaka, Todd; Alex Duyck; intel-wired-lan at lists.osuosl.org
Subject: Re: [Intel-wired-lan] [PATCH] igb: Enable RSS for i211 adapter

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


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