We have a global scheduler which takes care of bringing up new M, registering G, and handling system calls. However, it does not handle the actual execution of goroutines. This is done by an entity called Processor, which has its own internal scheduler and a queue called runqueue (runq in code) consisting of goroutines that will be executed in the current context. It also handles switching between various goroutines and so on:

// Denoted as P in runtime code 
type p struct { 
    id     int32 
    m     muintptr // back-link to associated m (nil if idle) 
    runq [256]guintptr 
 
    //... 
}