This is going to get more confusing in the future is the CPU's that have different core types get popular.

Kind of a late response but just stumbled here. Basically HT/SMT is what is known as a branch prediction queue. I.e. the cpu core is what actually does work, nothing will get done on a system without it hitting an actual core. What HT/SMT does is open up a queue to accept commands to be processed by the actual core and try to preload or 'predict' certain calls. For applications that are memory resident you can get a decent amount of benefit for this as the core when done with it's current task has the new data to load in at hand. If however this 'prediction' is wrong (i.e. data that was preloaded is not valid anymore; the heuristic 'guessed' a wrong path, etc.) then the 'preload' work has to be thrown out and goes back to a normal operation. Now, Where this fails miserably is when there is any workload that requires a hardware interrupt (e.g. disk i/o; network i/o; audio i/o; whatever). Basically really anything that is not in memory. hardware interrupts /CANNOT/ be predicted and *must* allocate a core to handle their load. Which means that if you have say something on a core and a HT/SMT queue loaded that queue will be vacated / flushed and instead the interrupt will be handled. This wastes time (it takes time (higher latency) to flush and time to wait for the core to finish up whatever it's already working on). This is why, in high performance systems HT/SMT is disabled (or you get cpu's that don't support it); Likewise functions like power saving functions (C states) (usually > C1) are disabled as those take time; in addition for really latency sensitive apps even dynamic frequency (raising/lowering/changing/ cpu frequency) is also disabled as that also takes time (cycles). Home users generally do not utilize their computers enough to notice this and they generally are running apps that (once loaded) are in memory. If you are doing i/o (hardware interrupt tasks) like running large NAS/SAN/DAS; doing high speed routing/firewall; or even professional multi channel audio this becomes an issue.

Google virtualization CPU over provisioning and head down that rabbit hole

@@LAWRENCESYSTEMS Thank you for indulging me.

They are just emojis

@@LAWRENCESYSTEMS lol well now i feel a bit dumb .. thanks brotha

Yes

No it will not put the unused cores into a wait state.

pfSense, unRAID, Ubuntu server and first two use hw passtrough.

I prefer XCP-NG

Netdata kzfaq.info/get/bejne/ftmhaciT0-C0pH0.html

@@LAWRENCESYSTEMS Awesome. Thank you

Pretty much yes

Yes and others.