On Mon, 31 Aug 2020 09:35:18 +0300
Andrew Rybchenko [off-list ref] wrote:

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multisegment packets.    

I hope it will be mentioned in the feature documentation in the future, but
I'm not 100% sure that it is required. See below.    

I suppose there is the hierarchy:
- applications configures DEV_RX_OFFLOAD_SCATTER on the port and tells in this way:
"Hey, driver, I'm ready to handle multi-segment packets". Readiness in general.
- application configures BUFFER_SPLIT and tells PMD _HOW_ it wants to split, in particular way:
"Hey, driver, please, drop ten bytes here, here and here, and the rest - over there"    

My idea is to keep SCATTER and BUFFER_SPLIT independent.
SCATTER is a possibility to make multi-segment packets getting
mbufs from main rxq mempool as many as required.
BUFFER_SPLIT is support of many mempools and splitting
received packets as specified.  

No.
Once again, drivers should take anything from application and rely on using
logic to choose best path. Modern CPU's have good branch predictors, and making
the developer do that work is counter productive.  

Please, add a bit more details. I simply can see relationship.
So, right now for me it looks like just misunderstanding.

Thanks,
Andrew.

Ok, documenting the existing behaviour is good. I was just concerned that this was
going to lead to more per-queue flags.