Messages in this thread | | | Subject | RE: [PATCHv2 net 1/2] sfc: Delete EFX_PAGE_IP_ALIGN, equivalent to NET_IP_ALIGN | Date | Tue, 14 May 2013 09:32:18 +0100 | From | "David Laight" <> |
| |
> The two architectures that define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS > (powerpc and x86) now both define NET_IP_ALIGN as 0, so there is no > need for this optimisation any more.
Hmmm.... even on x86 there will be a measurable cost in misaligned accesses - at least for some workloads.
If the DMA is able to write to a mis-aligned buffer and still perform aligned burst transfers mid-frame then 4n+2 aligning the rx buffer should be a win even on x86.
Note to hardware engineers: add an option to write two bytes of junk before the rx data :-)
David
| |