Multiple processors

[intersimi]

I want to test and compare 2 types of server. One server has 4 processors hyperthreaded (8 Virtual processors) running at 1.6Ghz. The other server has 2 processors hyperthreaded (4 Virtual Processors) running at 2.06Ghz.

From the downloaded version and with all defaults set, I get the following results:

4CPU
CPU Mark = 687.5

2CPU
CPU Mark = 743.2

Does this test take in to account all of the processors or would it just effectively test one processor?

Does it mean that the 2CPU server is CPU wise, faster than the 4CPU machine taking in to account all of the processors?

[David (PassMark)]

I don't know which version of PerformanceTest you used, but yes it should use all available CPUs (even virtual ones).

But if you want you can also manually set the number of processes to use from the configuration window.

If I had the choice I would pick the 2 fast CPUs, rather than the 4 slow ones. There are very very few applications on the market that can effectively use 4 (or 8 ) CPUs. So most of the time, for real life applications, you'll have one busy CPU and 7 idle CPUs. So if only 1 CPU can do the work, better that it is a fast one.

(Of course all this depends somewhat on the applications you are planning to run)

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David

[intersimi]

Thanks for replying. We are running Citrix and it is Multithreaded So all available CPU's are utilised fairly evenly.

In this instance, would you use double the amount of processors or double the processor speed. i.e. 4x 1.6Ghz or 2x 3.06 Ghz

I know it is a tough decision, but am trying to gauge other people views

[David (PassMark)]

I would still go with 2 CPUs. Becuase of,

1) Citrix will only thread well when you have a lot of users. If one user runs a big job (e.g. a big query in Access or re-paginating a 1000 page Word document) it will still run in one thread.

2) So in a fully load situation the 2 & 4 CPU situation is roughly the same. But in a low / medium load situation users will get things done faster with a faster CPU.

3) The faster CPUs are probably a newer model? Which means the bus speed is faster the cache is larger and it will a better feature set. (e.g. SSE)

4) 2 CPUs use less power than 4 (depending on the models)

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David

[intersimi]

Thanks for the Info Dave.

I will likely be running 5/6 servers with approximately, 40 user per server with a custom application which is not multithreaded. It seems that the number of processors would be utilised. My concern is whether I should use 2 Higher Spec CPU's or 4 lower spec CPU's. It seems your are biased towards the 2 CPU model due to the increased instrction sets within the newer arcitecture.

In the above scenario (1 server = 40 users over Citrix). Do you still hold the belief that 2 CPU model is better than 4 CPU?

[David (PassMark)]

There probably isn't much in it. But I still would have a slight preference for the 2 CPU system. I assume the price is about the same and all other factors (like the hard drive interface specs, network cards & warranty) are the same.

You might want to post the question to a Citrix forum as there might be someone with practical experience.

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David.

[intersimi]

Thanks Dave. I will do that