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

From: Aaron Lehmann (
Date: Sat Jan 27 2001 - 01:20:03 EST

On Sat, Jan 27, 2001 at 04:45:43PM +1100, Andrew Morton wrote:
> 2.4.1-pre10-vanilla, using read()/write(): 34.5% CPU
> 2.4.1-pre10+zercopy, using read()/write(): 38.1% CPU

Am I right to be bothered by this?

The majority of Unix network traffic is handled with read()/write().
Why would zerocopy slow that down?

If zerocopy is simply unoptimized, that's fine for now. But if the
problem is inherent in the implementation or design, that might be a
problem. Any patch which incurs a signifigant slowdown on traditional
networking should be contraversial.

Aaron Lehmann

please ignore me if I don't know what I'm talking about.
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