[kris_jag]

Hi all,

We recently replaced our four "ourself made" i7-980X 3.33 GHz computers with two Dell PowerEdge R820 (each with 4 Xeon E5-4650 2.70 GHz) servers. On old i7 computers were installed Windows Server 2008 R2 Standard, on R820 we have Windows Server 2008 R2 Enterprise. On R820 there is installed MS HPC, but it is not used yet - we are carrying out the Fluent computations by Remote Desktop (RDP).

Unfortunately the time computation on new servers is rather poor. According to CFP2006 Rates benchmarks from SPEC.ORG (parallel floating point calculations) R820 should be significantly faster than old computers (table.gif).
I know that they are only benchmarks, but...
Our R820 at the beginning were slower than two years' old i7. After some bios and operating system tuning by our hardware provider they are more or less the same as old (still a little slower) - instead of 50-100% faster...

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That was only background. Main reason of this post is a question - do someone know, why one thread could be calculated by two cores?

Example:
One Fluent calculation on 4 processes fl_mpi1400.exe (processes.gif)

Each process has 7 threads, but only one of them is "power demanding" (threads.gif).
3.14% of processor load equals 100% of one core load (32 cores in system).

But for these four processes/threads the eight cores is used, of average 50% usage (graphs.gif).

Why one thread is calculated by two cores (at least it looks like that)? Does anybody know?

I suppose that could(?) be a (one of) reason for poor performance.

Just one comment: Hyper Threating on both old and new computers is disabled.

Thanks for any help/advise.