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

To: jamal <hadi@xxxxxxxxxx>
Subject: Re: sendfile+zerocopy: fairly sexy (nothing to do with ECN)
From: Ion Badulescu <ionut@xxxxxxxxxxxxxxx>
Date: Mon, 29 Jan 2001 17:06:31 -0800 (PST)
Cc: Andrew Morton <andrewm@xxxxxxxxxx>, lkml <linux-kernel@xxxxxxxxxxxxxxx>, "netdev@xxxxxxxxxxx" <netdev@xxxxxxxxxxx>
In-reply-to: <Pine.GSO.4.30.0101270747210.24088-100000@xxxxxxxxxxxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx
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:
>
> http://www.cyberus.ca/~hadi/ttcp-sf.tar.gz
>
> 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:

[starfire]
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%


Ion

-- 
  It is better to keep your mouth shut and be thought a fool,
            than to open it and remove all doubt.


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