In a hyperthreaded CPU, for each processor core that is physically present, the operating system addresses two virtual or logical cores, and shares the workload between them when possible.
Relates to issues dealing with multiple processors
"First step would be to investigate why a processors with hyperthreading simultaneous multithreading could lead to poorer performances than a processors without this technology"
from question "I need a short C programm that runs slower on a processor with HyperThreading than on one without it"
"A quad core intel cpu s with hyperthreading enabled has 4 physical cores yet 8 logical processors hyperthreading creates 4 more logical processors"
from question "C/C++/Assembly Programatically detect if hyper-threading is active on Windows, Mac and Linux"
"More modern processors handle hyperthreading better than older processors"
from question "8 logical threads at 4 cores will at a maximum run 4 times faster in parallel?"
"You may find that hyperthreading helps more on code that is using large amounts of memory so that the processors is regularly blocked on fetching from memory"
from question "Hyper-threading Performance Comparison"
"In computer 1 the eigen3 performance is worse because the number of total processors virtual + physical - â due to hyperthreading is greater than the number of physical processors"
from question "Eigen3 matrix multiplication performance dependent of the processor?"