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Re: [condor-users] Pc's with hyperthreading

On Fri, Apr 23, 2004 at 10:30:32AM +1000, Ian.McLeod@xxxxxxxx wrote:
> Our latest crop of Pc's are coming with hyperthreading 
> The computers are pretending to have 2 cpu's
> Two questions 
> 1. How do I want to convince condor that it really has only one CPU
>    I found the NUM_CPUS in the config file - 
>    but I note that its use is not recommended. 

For disabling hyperthreading, that is the recommended solution.
Many machines will let you disable hyperthreading in the BIOS
as well.

In Condor 6.6.5 (still a few weeks off), we have a 

option, which will detect if some of the CPUs are hyperthreads
and not count them, so you can set this as a global config file.

It's currently a Linux-only option, we'll see if we can make it work
on Windows too.

> 1. How good is the hyper-threading technology ? 
>    Should I be trying to convince condor that it really has only one CPU

As with all things HPC, it depends on the app :)

For the most part, here at UW we've disabled it to keep the RAM per 
virtual machine high.

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