Hello,

I have a P4 with 2,8 GHz and HT. I am running CPDN on one CPU and the Seti Classic on the other (emptying the queue).
I am considering to run CPDN only and use HT for that. After reading through the FAQ, Forum and other sites, I am still a little puzzeled, so let me see if I got it right:

1) I can run CPDN under BOINC 4.13 on a computer with HT. And (usually) it does not crash. (There were some earlier messages somewhere where it did.)

2) If I do that, my computer works on 2 WU instead of one, so I need twice as much disk space (2x 700 MB), too.


If the above is right, I have more questions:

a) If I run CPDN only, will HT actually accelerate the calculation?

b) If I run CPDN only, will the WUs still be swapped every 60 minutes (or whatever time intervall I set under preferences)? What/How will they be swapped, e.g. switch processors?

c) Is there a way to temporarily (e.g. 30 minutes) to suspend calculation for just one of the two?

Thanks lot for your help!

Friedrich

> I have a P4 with 2,8 GHz and HT. I am running CPDN on one CPU and the
> Seti Classic on the other (emptying the queue).
> I am considering to run CPDN only and use HT for that. After reading
> through the FAQ, Forum and other sites, I am still a little puzzeled,
> so let me see if I got it right:

>1) I can run CPDN under BOINC 4.13 on a computer with HT. And (usually) it
>does not crash. (There were some earlier messages somewhere where it did.)

I have two dual Xeon HT machines running four models each, they're doing fine to date. Many others are running two models on single physical CPU HT machines without any problems.


> 2) If I do that, my computer works on 2 WU instead of one, so I need twice
> as much disk space (2x 700 MB), too.

Yes, although all you <i> have to </i> have is 600MB of <i>free space</i> anytime you resume either model AFAIK.

&gt; If the above is right, I have more questions:

&gt; a) If I run CPDN only, will HT actually accelerate the calculation?

Nope, both models will run slower but your overall throughput will increase, ie. 2 models in 30 days instead of 1 model in 20 days, those sort of figures.

&gt; b) If I run CPDN only, will the WUs still be swapped every 60 minutes
&gt; (or whatever time intervall I set under preferences)? What/How will
&gt; they be swapped, e.g. switch processors?

Nope, they just run all the time - I've found I get a slight increase in performance if I use 'Task manager' to set the affinity of each model to a single CPU but it is a very small increase.

&gt; c) Is there a way to temporarily (e.g. 30 minutes) to suspend calculation
&gt; for just one of the two?

Yes, effectively; Set affinity of both models to a single CPU, ie. rightclick on a process in 'task Managaer' (xxx_um_xxx) and set affinity to the same CPU - this will leave you one CPU completely free - I've just now tested this on one of my dual Xeon machines &amp; it works. Both models will still run but at roughly half speed whilst limited to using a single CPU for both.

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As Nick said, yes it will speed the calculation through running two models at once. I've seen, and others have commented, that it appears to be about a 15% increase in throughput from hyperthreading, i.e. my P4 can do two models in ~21.5 days using HT, but with HT turned off, it would take ~25 days to do two models.

edited out...

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Thanks a lot for your answers!
Once the queue for Seti clasic is empty I am ready to switch from 1 to 2 CPUs.

Thanks again!

Friedrich