Proliant BL465c-G6 and Processor Affinity

[Gerhard Sommer]

We are running an ASP.NET application on a Proliant BL465c-G6 with 12 Cores (AMD Opteron 2435, 2.6 GHz).

On the previously used G1 Hardware with 4 Cores (AMD Opteron, 2.8 GHz) the execution time of the same request is 2 seconds, while on the newer G6 hardware it is 4 seconds.

If we configure processor affinity in .NET, so that the application is bound to a specific core, we get 2.3 seconds with the G6 hardware. But performance under stress (an external load balancer distributes the load to 12 identical applications and each application has its own dedicated CPU) is worse than in another configuration without affinity (all 12 applications can use any CPU).

Does anyone know, how to get the perfomance of the older G1 hardware, when the load is low, without having to use CPU affinity and thus loosing performance, when the load on the machine is high?

What is the difference between G1 and G6 hardware, which results in almost half the performance of the newer hardware?

Might there be any BIOS setting, that could influence performance so much?

The OS is Windows Server 2003 Enterprise SP2 in both cases. The application uses .NET Framework 3.5, but most of the execution time is consumed in a 3d-party COM component (.NET COM Interop).

Best regards,
Gerhard