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Journeyman III

Performance Opteron 2435 (2Cpu 6core) - can anybody help?

Opteron 2435 w Windows 2008 Server SP2 64 bit w disappointing performance


Hi all,

Performance on our new 2 CPU 6core 2.66Ghz Opterons 2435 is a bit disappointing and I have no idea where to look or what I can do about it.  I hope somebody can put us in the right direction.

Comparison is done with a 2 CPU Intel Xeon X5450 3.00Ghz (4core, also Windows 2008 Server 64 bit) - and also with my Windows XP Desktop.

The application (C#) uses multiple threads to read/process/write multiple files and runs about 37 minutes on Opteron and 23 minutes on Intel. CPU usage on Opteron is about 15% average, on Intel (exact same program and data ) about 30%. For some reason it just doesn't use all that cpu power. Somewhere seems to be a bottleneck (it is not IO).

We also created a little test application (see attached code) that only does some integer processing and this shows the same (even worse) behavior on Opteron being slower. Java or .Net doesn't seem to make a difference with this one.

We are stuck at the moment and would really appreciate if anybody can give some hints.

Many thanks,



int num; int i; int factor; bool isprime; DateTime startTime = DateTime.Now; textBox2.Text = "Working..."; textBox2.Refresh(); for (num = 2; num < Convert.ToInt64(textBox1.Text); num++) { isprime = true; factor = 0; // see if num is evenly divisible for (i = 2; i <= num / 2; i++) { if ((num % i) == 0) { // num is evenly divisible -- not prime isprime = false; factor = i; } } } DateTime stopTime = DateTime.Now; TimeSpan elapsedTime = stopTime - startTime; textBox2.Text = elapsedTime.ToString();

3 Replies
Adept III

Although .NET Platform is an easy to use toolbox, I'm not sure about its performance, especially in case of multithreading. If you wish to achieve a maximum performance of your hardware, I think you'd use some nice optimized compilers like PathScale and/or PGI.

As for your percentage: 15% for six-core Opteron means that your application uses only one core (100% / 6 cores = 16,7%, which is near at your 15%). 30% of quad-core Xeon, I think, means the same (100% / 4 cores = 25%, which is near at your 30%).


Thanks for the answer, I will look into the tools.

What me struck was that it seems that 1 core of Intel X5450 seems to be faster than 1 core of Opteron 2435 - ist that possible? I thought the Opteron was faster or at least equivalent - but I am not an expert here.

I definitely get more throughput on Intel. Also the simple calculation from the code runs much faster on the (single core) Intel (with java and .net same behaviour).



Don't forget that your Xeon has more higher frequency (3.0 vs. 2.66 GHz of Opteron), larger and faster cache (and FSB), and more higher IPC (4+ vs. 3 of Opteron). So, yes, in your case with unoptimized software your Opteron may work slower than your Xeon. But if you'll try to parallellize your software, maybe you'll achieve even greater performance on your Opteron.