performance question

Jim Carter jimc at
Thu Sep 12 02:07:18 EST 2002

On Wed, 11 Sep 2002, Marc Cousin wrote:
> I am currently using the 12c driver, and i'm wondering if what i'm seeing is
> normal :
> when transfering from another machine at full speed (about 550 kbytes/s), the
> cpu load gets as high as 75% on my computer, which is an athlon 700...
> this number seems rather high to me, so i'm asking...

No, it's not normal.  Driver version 0.12* is broken.  You should revert to
version 0.11b, available at:
Version 0.13 is currently being tested; check back from time to time.

See README.txt in the above directory for a few details.

With the right driver, you should see essentially zero CPU usage.  WEP
takes CPU cycles on the card, but no CPU on the host machine, and with
a modern CPU, ssh encryption is also cheap.  For example, a Dell Optiplex
GX-240 with 1.8 Ghz Intel Pentium-4 CPU did "tar cf - /usr/src/linux/. |
ssh otherhost 'cat - > /tmp/linux.tar'" over a 10 MHz Ethernet
connection, and the ssh process used 5.9% of CPU time.  The other host was
a Sun Enterprise-3500, so I'm pretty sure it was not the bottleneck; the
Ethernet was.

James F. Carter          Voice 310 825 2897    FAX 310 206 6673
UCLA-Mathnet;  6115 MSA; 405 Hilgard Ave.; Los Angeles, CA, USA  90095-1555
Email: jimc at (q.v. for PGP key)

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