linuxppc_2_4_devel on walnut

Kenneth Johansson kenneth.johansson at
Sat Nov 17 07:47:11 EST 2001

Dan Malek wrote:
> Kenneth Johansson wrote:
> > But "time dd if=/dev/zero of=testing bs=1024k count=100" on a nfs mouted fs
> > used to be 18s and is now 21s, a 16% slowdown not that I care much but still
> > quite a large difference.
> What versions of kernels/drivers are you comparing?  Do you do this
> back-to-back with the same NFS server, or have you introduced more
> variables into your testing?  This is why specially prepared network
> performance testers are better suited for discussion.

This was to the same nfs server on a live network. I did the test only two
times on the first kernel version that was checke out a few hours before the
mail was posted last friday.

This was not done to benchmark anything but a way for me to verify what speed
the networks was using 10/100 Mb was at the time reported wrong by the

The reason I run it twice was that I thougt 5,5MB/s was not so great but the
second run had the same number. Then I upgraded the tree to a version that
had Armin Kusters changes and just for fun run the test again.

If I test only tcp/ip over the network I now get this..
walnut:/tmp# time dd if=/dev/zero  bs=1024k count=100 | nc -q0 <server> 9
100+0 records in
100+0 records out

real    0m14.838s
user    0m0.370s
sys     0m14.380s

If I do the same from a intel 400MHz kernel 2.2.20 I get
[innkeon at spawn innkeon]$time dd if=/dev/zero  bs=1024k count=100 | nc -q0
<server> 9
100+0 records in
100+0 records out

real    0m12.838s
user    0m0.110s
sys     0m1.890s
7,8 MB/s

hmm funny the difference is also 16%

(nc is the netcat program.)

Kenneth Johansson
Ericsson Business Innovation AB   Tel: +46 8 404 71 83
Viderögatan 3                     Fax: +46 8 404 72 72
164 80 Stockholm                  kenneth.johansson at

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