[Freesurfer] hyperthreading

Hello,

Question about eking out maximum machine performance: Is there a performance advantage (or alternatively penalty) for running twice as many FreeSurfer jobs (simultaneously) as physical CPUs on a Linux machine with HyperThreading enabled CPUs? That is, say you have two physical cores with HyperThreading -- the Linux OS treats this as four logical processors. However, given that Freesurfer is very 'execute' intensive is there any advantage to be gained by running 4 rather than 2 FS jobs simultaneously? Or will the total time per brain with 4 simultaneous jobs be (on average) just twice as long?

thanks, Mike H.