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

["Brandes, Shai" <shaibran@amazon.com>]

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@amd.com>
> Sent: Friday, March 8, 2024 7:24 PM
> To: Brandes, Shai <shaibran@amazon.com>
> Cc: dev@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@amazon.com wrote:
> > From: Shai Brandes <shaibran@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.