[PATCH v3 07/33] net/ena: restructure the llq policy setting process

[Ferruh Yigit]

On 3/10/2024 2:29 PM, Brandes, Shai wrote:
> 
> 
>> -----Original Message-----
>> From: Ferruh Yigit <ferruh.yigit at amd.com>
>> Sent: Friday, March 8, 2024 7:24 PM
>> To: Brandes, Shai <shaibran at amazon.com>
>> Cc: dev at dpdk.org
>> Subject: RE: [EXTERNAL] [PATCH v3 07/33] net/ena: restructure the llq policy
>> setting process
>>
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>>
>>
>> On 3/6/2024 12:24 PM, shaibran at amazon.com wrote:
>>> From: Shai Brandes <shaibran at amazon.com>
>>>
>>> The driver will set the size of the LLQ header size according to the
>>> recommendation from the device.
>>> Replaced `enable_llq` and `large_llq_hdr` devargs with a new devarg
>>> `llq_policy` that accepts the following values:
>>> 0 - Disable LLQ.
>>>     Use with extreme caution as it leads to a huge performance
>>>     degradation on AWS instances from 6th generation onwards.
>>> 1 - Accept device recommended LLQ policy (Default).
>>>     Device can recommend normal or large LLQ policy.
>>> 2 - Enforce normal LLQ policy.
>>> 3 - Enforce large LLQ policy.
>>>     Required for packets with header that exceed 96 bytes on
>>>     AWS instances prior to 5th generation.
>>>
>>
>> We had similar discussion before, although dev_args is not part of the ABI, it
>> is an user interface, and changes in the devargs will impact users directly.
>>
>> What would you think to either keep backward compatilibity in the devargs
>> (like not remove old one but add new one), or do this change in
>> 24.11 release?
> [Brandes, Shai] understood. 
> The new devarg replaced the old ones and added option to enforce normal-llq mode which is critical for our release.
> As you suggested, we will keep backward compatibility and add an additional devarg for enforcing  normal-llq policy.
> That way, we can easily replace it in future releases with a common devarg without the need to make major logic changes.
> 

ack.