Messages in this thread | | | Subject | Re: is CONFIG_PACKET_MMAP always a win? | Date | Fri, 22 Feb 2002 19:57:33 +0000 (GMT) | From | Alan Cox <> |
| |
> > You can process them in the ring buffer. If you can't keep up then you > > are screwed any way you look at it 8) > > That still doesn't avoid copying: af_packet copies the whole packet (if > you want the whole packet) from the original skbuff to the ring buffer.
I'd make a handwaved claim that the first copy of the packet from a DMA receiving source is free. Its certainly pretty close to free because the overhead of sucking it into L1 cache will dominate and you need to do that anyway.
Zero copy is sometimes a false friend. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |