On 2011-01-08 5:36 PM, Ben Greear wrote: > On 01/08/2011 04:20 PM, Felix Fietkau wrote: >> I think this should be dependent on packet size, maybe even based on the >> architecture. Especially on embedded hardware, copying large frames is >> probably quite a >> bit more expensive than allocating large buffers. Cache sizes are small, >> memory access takes several cycles, especially during concurrent DMA. >> Once I'm back home, I could try a few packet size threshold to find a sweet >> spot for the typical MIPS hardware that I'm playing with. I expect a visible >> performance regression from this patch when applied as-is. > > I see a serious performance improvement with this patch. My current test is > sending 1024 byte UDP > payloads to/from each of 60 stations at 128kbps. Please do try it out on > your system and see how > it performs there. I'm guessing that any time you have more than 1 VIF this > will be a good > improvement since mac80211 does skb_copy (and you would typically be copying > a much smaller > packet with this patch). > > If we do see performance differences on different platforms, this could > perhaps be > something we could tune at run-time. What kind of system are you testing on? If it's a PC, then the performance characteristics will be completely different compared to embedded hardware. I've had to remove a few copybreak-like implementations from various ethernet drivers on similar hardware, because even taking the hit of unaligned load/store exceptions (which are already *very* expensive on MIPS) was less than copying the full packet data, even with packet sizes less than what you're using.
I don't have suitable test hardware with me right now, but I'll do some tests in a week or so. - Felix _______________________________________________ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
