[R] Hardware oddity - linux/windows

[Prof Brian Ripley]

Do you have an anti-virus software running?  That's about what I see when 
Sophos is switched on.

On 9 Sep 2003, michaell taylor wrote:

> 
> Hi,
> 
> I am trying to figure out why a new machine is running my R script so
> slowly.  
> 
> The script was developed on a Linux , dual 2.8 xeon processor machine
> with 4GB ram.  On this machine, the script runs in about an hour (it
> creates lots of multilevel simulations). While running, 100% of a single
> processor (50% of dual processor) is used consistently during the entire
> run, about 800 MB of ram is utilized.  Xeon hyperthread condition
> (on/off) seems not to matter to performance.  While the script runs, I
> am using the "other" processor for miscellaneous emailing, editing, etc.
> 
> Moving the script to a windows XP machine with nearly identical hardware
> configuration (2.8 dual xeon, 4.5 GB ram) the script takes nearly 2
> hours.  Oddly, the maximum cpu load on this machine is 50% of a single
> processor (25% of dual processor) during the run - which seems
> consistent with the doubling of total processing time. While running
> this script, this machine does no other tasks whatsoever. 

The last is very, very unlikely.

> Both machines have at least double the memory required for the task,
> both utilize fast scsi drives and all data is stored locally on the
> drive (no data on network drives).  Moreover, being a simulated problem,
> very little data is read/written to drives during the process.
> 
> Anyone have ideas as to why the Windows machine is so slow?
> 
> Thanks in advance.
> 
> Michaell Taylor
> 
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> 
> 

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595