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SubjectRe: sendfile+zerocopy: fairly sexy (nothing to do with ECN)
On Sat, 27 Jan 2001, jamal wrote:

> > starfire:
> > 2.4.1-pre10+zerocopy, using sendfile(): 9.6% CPU
> > 2.4.1-pre10+zerocopy, using read()/write(): 18.3%-29.6% CPU * why so much variance?
> >
> What are your throughput numbers?

11.5kBps, quite consistently.

BTW, Andrew's new tool (with 8k reads/writes) has shown the load in the
read/write case to be essentially the lower margin of the intervals I got
in the first mail.

> Could you also, please, test using:
> post both sender and receiver data. Repeat each test about
> 5 times.

I've tried it, but I'm not really sure what I can report. ttcp's
measurements are clearly misleading, so I used Andrew's cyclesoak instead.
The numbers are (with 2.4.1-pre10+zerocopy):

[starfire, hw csum & sg enabled]
sending with sendfile: 10.0-10.2%
sending with send/write: 13.5-13.7%
receiving: 20.0-20.2%

[starfire, hw csum & sg disabled]
sending with sendfile: 18.1-18.3%
sending with send/write: 13.9-14.1%
receiving: 24.3-24.5%

[eepro100, i82559, no hw fancies]
sending with sendfile: 16.2-16.4%
sending with send/write: 12.0-12.2%
receiving: 21.5-21.7%

Same tests, this time with 2.4.1-pre10 vanilla:

sending with sendfile: 18.1-18.3%
sending with send/write: 12.5-12.7%
receiving: 23.0-23.1%

[eepro100, i82559]
sending with sendfile: 16.7-16.9%
sending with send/write: 12.0-12.2%
receiving: 20.8-20.9%


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than to open it and remove all doubt.

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