Weird behavior with dual core Opteron

[ROcHE]

If I run Cinebench on one cpu or encode some video file with Virtualdub without setting the affinity manually I get this weird cpu usage:

Screenshot

Why doesn't it use only one core at 100% ?

 

[HPTech]

The app is multithreaded, so it distributes load accross the cores.

MikeHP

 

[ROcHE]

I would not consider Cinebench 9.5 forced to use one core only as "multithreaded". Might be wrong tough.

 

[krotchy]

My computer does this even with prime 95 running a single instance. Also my old Northwood did this with its hyperthreading. I think windows seems to create two threads out of a single thread and throttles down both cores so that each does half the work. This probably helps spread out heat dissipation to keep one core from always running and wearing out before the other.

 

[robertk2012]

Thats normal in apps that arent multithreaded. Some will not distribute the load like that but many will. I think performance is better (slightly) with just one core however.

 

[aka1nas]

It just means that windows is switching the thread between cores rapidly. Depending on the system utilization, this is probably a tiny bit slower as context switching isn't free.