On 2011-06-07, Laurie Gellatly <laurie.gella...@netic.com> wrote: > I tried to enable this before without success.
Ah yes, I saw your (unanswered) post from a few years back asking about this. I was hoping there had been some progress since then. > I agree that its a waste of processor time when it can be performed > in hardware. The last time I did some profiling, IP checksum calculation was a pretty significant bottleneck for TCP throughput. Back in the NetBSD stack days, I got about a 20% improvement in throughput by writing my own assembly-language IP checksum routine for ARM7. The FreeBSD C implementation and more recent versions of gcc do almost as well as hand-tuned assembly, but it's still a big percentage of CPU usage in TCP communications -- and it will be even worse now that I have a chip that does scatter-gather DMA. A part for US $4 that has IP checksum offloading and scatter-gather DMA. Back when I was a new grad... > Must we look at the latest BSD code to see how to implement this? Maybe. Or there might be a simpler way to do it. I would guess that the current FreeBSD has an API to configure this on a per-interface basis at run-time. If we can assume that there is only one external interface, then we don't need any API or runtime checks, just a few strategic #if/#endif pairs and some CDL to control them. -- Grant -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss