On Sun, 2002-07-21 at 14:21, rwhron@earthlink.net wrote:
> In Carl Staelin and Larry McVoy's 98 Usenix paper they wrote:
>
> "It is interesting to compare pipes with TCP because the TCP benchmark is
> identical to the pipe benchmark except for the transport mechanism. Ideally,
> the TCP bandwidth would be as good as the pipe bandwidth. It is not widely
> known that the majority of the TCP cost is in the bcopy, the checksum, and
> the network interface driver. The checksum and the driver may be safely
The paper however ignored something else we do which is why you see
csum_partial_copy_generic. On a modern processor the cost of fetching
and storing memory is so high compared to the throughput of the
processor that it is actually much more effective to fold the copy and
checksum together. Generally the copy/checksum has the same speed as a
pure copy anyway
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This archive was generated by hypermail 2b29 : Tue Jul 23 2002 - 22:00:35 EST