[Beowulf] network transfer issue to disk, old versus new hardware

[Bogdan Costescu]

On Mon, 4 Jun 2007, David Mathog wrote:

> Athcool does cut the idle temperatures of the nodes considerably, 
> but apparently also prevents them from performing this sort of 
> transfer at full speed, whether or not buffer is used.

Well, near the top of the athcool website there is a warning and one 
the listed items is 'a slowdown in harddisk performance' - so nothing 
new here ;-)

> Which is interesting because it didn't have any measurable effect on 
> CPU bound processes.  I had thought it would shut itself off and get 
> out of the way when the CPU rate was high, but apparently not.

CPU bound and I/O bound processes use the processor in different 
ways... When doing only I/O, the processor is often waiting for the 
hardware, so the load on the processor is low.

-- 
Bogdan Costescu

IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu at IWR.Uni-Heidelberg.De
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