DL380 - 1 Processor or 2 ?????

[Rob Smith]

Compaq DL380, when the system POSTs it says that is has 1 processor. When I open the system up it has 1 processor. Yet in WIN2K, Task Manager and System Performance Monitor, it says that is has 2 CPUs. What gives? Anybody else ever run into this situation before?

Rob

[Tom Patterson]

Just guessing, but it sounds like perhaps the multi processor driver has been loaded. I know that if you have two processors but have the uniprocessor driver loaded you only see 1 in taskman. Perhaps the reverse is true. You can check this out by going into Device Manager and expanding Computer. If it doesn't say Uniprocessor it's easy enough to change by simply updating the driver.

[Patrick Rouse · Accepted solution]

Is it a DL380 (G3) with Xeon Processor 2GHz or Higher? If so then Windows will see two CPU's because hyperthreaded chips have one physical & one logical CPU.

http://www.intel.com/products/server/processors/server/xeon/index.htm

http://h18004.www1.hp.com/products/servers/proliantdl380/description-g3.html

[Erki Rajangu]

Probably it is Intel Xeon indeed but the hyper-threading is described otherwise: one physical processor which consist of two logical processors. Processors with Hyper-Threading technology can improve the performance of applications by permitting a single processor to process data as if it were two processors by executing instructions from different threads in parallel rather than serially. However, the potential performance improvement can be only obtained if an application is multithreaded by parallelization techniques.

[Jens Baumann_2]

Yes, Hyperthreading causes a single physical processor to appear as two processors under Windows 2000, XP and 2003 (AFAIK it does not work at all under NT4). The newer P4/Xeon have two logical CPUs in one single physical CPU. It's not the same as two separate physical CPUs, since the logical ones share e.g. the Cache, so the performance gain is not as big as the one you have when switching from one physical CPU to two. Still, it is there. Windows 2000 does not realize that there is only one physical CPU present, so applications (e.g. Windows itself) which rely on the CPU number for licensing purposes react as if double the number of physical CPUs were present. Might cause problems and you might have to turn off Hyperthreading in the Bios if your application does not run because the CPU number is higher than the one you licensed for. Windows XP and 2003 "know" about Hyperthreading and even have some optimizations for it.

[Blairon Philippe]

Hi all,

Yes I expreinced the same probleme with Xeon bi processor server. Windows 2000 see 4 processor.

Right now I havn't seen any problem with that expect that it's confused on the task manager.

[Blairon Philippe]

Hi all,

Yes I experienced the same probleme with Xeon bi processor server. Windows 2000 see 4 processor.

Right now I havn't seen any problem with that expect that it's confused on the task manager.

[Juan Carlos Ramirez]

The new Intel XeonTM processors incorporate Intel's Hyper-Threading Technology, which makes one physical processor look like two logical processors to the OS and applications. These two 'logical' processors on a single physical processor can execute different tasks simultaneously using shared hardware resources. By allowing the processor to use on-die resources that would otherwise have been idle, Hyper-Threading Technology provides a performance boost on multi-threading and multi-tasking operations. Not all operating systems take advantage of the XeonTM Hyper-Threading features.

http://h18004.www1.hp.com/products/servers/technology/hyper-threading.html

Intel suggests disabling HyperThreading on all WIn2K, NT, and prior operating systems. Only new operating systems include optimizations for HT Technology.

http://www.intel.com/support/platform/ht/os.htm
Microsoft expects performance to vary depending on the application, system configuration, and version of Windows that is used.

Although Windows 2000 is compatible with Hyper-Threading Technology, we expect customers will get the best performance from Hyper-Threading Technology using Windows .NET Server. This is because the Windows .NET Server Family is engineered to take full advantage of the logical processors created by Hyper-Threading Technology.

http://www.microsoft.com/windows2000/docs/hyperthreading.doc

On a system with Intel HTT enabled, Microsoft requires only one license for each physical processor. Therefore, customers only need to acquire one processor license for each physical processor even though the software may count one physical processor as two logical processors.

http://www.microsoft.com/sql/howtobuy/SQLonHTT.doc