Allocation of small packets on Rx

Hi folks !

For a driver that gets small packets "inline" in the rx descriptors, I
allocate the skb in the rx poll and copy the data to it.

Should I allocate an skb of the just the right size for the packet (+
eventual alignment) or is there any benefit to allocating all skb's the
same size ?

The max size of those "inline" packets is 256 bytes and the driver today
always allocate that. Does that "help" the allocator some way or should
I just allocate what is needed for each packet ?

Cheers,
Ben.