[Beowulf] ethernet switch, dhcp question

Ken Linder (kc7rad) kc7rad at radstream.com
Mon Oct 4 23:04:45 EDT 2004


Paul,
I don't think the DHCP has much to do with mpich performance...  I think the
only additional overhead it adds is when the node computer first comes
on-line.  It just sends a request to the DHCP server for an IP address (and
gateway, netmask, etc... I think :-)

Now, what WILL affect your performance is using your campus network.  You
are relying on the cable and infrastructure of that network.  Your cluster
is also competing for resources with all other network users, at the switch
level.  One could argue that this delay is negligable but if you add all the
delays that may exist in a small public network, it could be considerable.

I recommend you spend a little money and get yourself a switch.  I just saw
an 8-port on e-bay for $13.  I suggest you make your own cables.  For me
anyway, it is an almost cathartic release for me to build my own cables. :-)

With your own switch, you control the traffic.  If you do this and response
time is still slow, at least you have your own network to analyze.

Ken
www.radstream.com
----- Original Message ----- 
From: "JOHNSON,PAUL C" <redboots at ufl.edu>
To: <Beowulf at beowulf.org>
Sent: Monday, October 04, 2004 4:31 PM
Subject: [Beowulf] ethernet switch, dhcp question


> All:
>
> Im fairly new to beowulf clusters so please excuse the question if
> it is trivial.  Ive installed mpich on several computers and have
> run several programs but the performance seems a little slow.  All
> the computers in my lab are connected directly to the campus
> network.  Would I see an increase in performance if I instead had
> slaves connected through a switch in my room connected to a master
> computer using dhcp to assign ip's?
> Thanks for any help,
> Paul
>
> --
> JOHNSON,PAUL C


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