Hyperthreading question.

[Deders]

If a program is using 100% of a hyperthreaded core, but 0% of its related actual core, does this mean it has access to 100% of the core and will be running at full performance?

 

[ShintaiDK]

Yes.

As such, both cores you see via HT are equal.

 

[Nothingness]

If a program is using 100% of a hyperthreaded core, but 0% of its related actual core, does this mean it has access to 100% of the core and will be running at full performance?

If you completely disable HT you might see a difference in performance, since part of CPU resources are reserved for handling HT (or at least that used to be the case for instance on Nehalem where the ROB was split when HT is enabled).

 

[Deders]

Thanks