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Message-ID: <c2c94aa3-c557-4a74-82fc-d88821522a8f@shopee.com>
Date: Thu, 2 Jan 2025 16:43:18 +0800
From: Haifeng Xu <haifeng.xu@...pee.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: Tony Nguyen <anthony.l.nguyen@...el.com>,
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 2025/1/2 16:13, Eric Dumazet wrote:
> On Thu, Jan 2, 2025 at 4:53 AM Haifeng Xu <haifeng.xu@...pee.com> wrote:
>>
>> Hi masters,
>>
>> We use the Intel Corporation 82599ES NIC in our production environment. And it has 63 rx queues, every rx queue interrupt is processed by a single cpu.
>> The RSS configuration can be seen as follow:
>>
>> RX flow hash indirection table for eno5 with 63 RX ring(s):
>> 0: 0 1 2 3 4 5 6 7
>> 8: 8 9 10 11 12 13 14 15
>> 16: 0 1 2 3 4 5 6 7
>> 24: 8 9 10 11 12 13 14 15
>> 32: 0 1 2 3 4 5 6 7
>> 40: 8 9 10 11 12 13 14 15
>> 48: 0 1 2 3 4 5 6 7
>> 56: 8 9 10 11 12 13 14 15
>> 64: 0 1 2 3 4 5 6 7
>> 72: 8 9 10 11 12 13 14 15
>> 80: 0 1 2 3 4 5 6 7
>> 88: 8 9 10 11 12 13 14 15
>> 96: 0 1 2 3 4 5 6 7
>> 104: 8 9 10 11 12 13 14 15
>> 112: 0 1 2 3 4 5 6 7
>> 120: 8 9 10 11 12 13 14 15
>>
>> The maximum number of RSS queues is 16. So I have some questions about this. Will other cpus except 0~15 receive the rx interrupts?
>>
>> In our production environment, cpu 16~62 also receive the rx interrupts. Was our RSS misconfigured?
>
> It really depends on which cpus are assigned to each IRQ.
>
Hi Eric,
Each irq was assigned to a single cpu, for exapmle:
irq cpu
117 0
118 1
......
179 62
All cpus trigger interrupts not only cpus 0~15.
It seems that the result is inconsistent with the RSS hash value.
Thanks!
> Look at /proc/irq/{IRQ_NUM}/smp_affinity
>
> Also you can have some details in Documentation/networking/scaling.rst
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