Re: sendfile+zerocopy: fairly sexy (nothing to do with ECN)

[kuznet@xxxxxxxxxxxxx]

Hello!

> The box has 130 mbyte/sec memory write bandwidth, so saving
> a copy should save 10% of this.   (Wanders away, scratching
> head...)

Did you hope to get negative load? It is unlikely. 8)

You had nic->skb mem->page mem->user mem and saved only one copy,
moreover that copy which happens back-to-back through cache.

BTW no need to scratch head, profiler exists to help to answer
such questions.

Alexey