You can see details of SMT using the smtctl command (but this is only executable by 'root' and can be a bad thing if run with the wrong arguments... i.e. it can turn off SMT).

smtctl

Things like OEM and topas see each thread as a cpu and therefore show 4 cpus, when in fact they are all just simultaneous threads on the same core... which can be very misleading... to make matters worse 4 threads cannot do the same work as 4 dedicated cores... so even cpu utilisation figures can be skewed... i.e. if you are running 1 transaction in 1 second on 1 thread, you won't be able to run 2 transactions in 1 second using 2 threads (but you might get 2 transactions in 1.5 seconds using 2 threads instead of the 2 transactions in 2 seconds that you would expect from a single thread... i.e. it makes better use of the cores than single threading but there are still bottlenecks that stop 2 transactions running at full speed through the same cpu core at the same time)... if you looked at topas whilst your hypothetical 1 transaction in 1 second was running on 1 thread you would see cpu utilisation of 25% on a core with 4 threads (which just isn't true).

Bibliography