netdev - Re: [Question] ixgbe：Mechanism of RSS

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Message-ID: <bb5dbf24-ef80-4220-8b07-40eed9ac15ae@intel.com>
Date: Wed, 8 Jan 2025 13:06:20 -0800
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: Haifeng Xu <haifeng.xu@...pee.com>, Edward Cree <ecree.xilinx@...il.com>,
	Eric Dumazet <edumazet@...gle.com>, Aleksandr Loktionov
	<aleksandr.loktionov@...el.com>, "Kwapulinski, Piotr"
	<piotr.kwapulinski@...el.com>
CC: Przemek Kitszel <przemyslaw.kitszel@...el.com>, "David S. Miller"
	<davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, <linux-kernel@...r.kernel.org>,
	<netdev@...r.kernel.org>, <intel-wired-lan@...ts.osuosl.org>
Subject: Re: [Question] ixgbe：Mechanism of RSS



On 1/7/2025 7:36 PM, Haifeng Xu wrote:
> 
> 
> On 2025/1/8 01:16, Tony Nguyen wrote:

...

>>
>> What's your ntuple filter setting? If it's off, I suspect it may be the Flow Director ATR (Application Targeting Routing) feature which will utilize all queues. I believe if you turn on ntuple filters this will turn that feature off.
> 
> Yes, our ntuple filter setting is off. After turning on the ntuple filters, I compare the delta of recieved packets,
> only 0~15 rx rings are non-zero, other rx rings are zero.
> 
> If we want to spread the packets across 0~62, how can we tune the NIC setting?
> we have enabled 63 rx queues, irq_affinity and rx-flow-hash, but the 0~15 cpu
> received more packets than others.

As Jakub mentioned earlier, HW RSS is only supported on this device for 
16 queues. ATR will steer bi-directional traffic to utilize additional 
queues, however, once its exhausted it will fallback to RSS, which is 
why CPUs 0-15 are receiving more traffic than the others. I'm not aware 
of a way to evenly spread the traffic beyond the 16 HW supported RSS 
queues for this device.

Thanks,
Tony

> Thanks!