task_rq(p)

task_rq(p)  获取进程p所在的runqueue的首地址
--------------------------------------------
#define task_rq(p)      cpu_rq(task_cpu(p))
#define cpu_rq(cpu)     (&per_cpu(runqueues, (cpu)))


task_cpu(p) 获取进程p所在CPU的编号
-------------------------------------------
static inline unsigned int task_cpu(const struct task_struct *p)
{
    return p->thread_info->cpu;
}

cpu_rq(cpu) 获取编号为cpu的处理器的runqueue的首地址
--------------------------------------------
#define per_cpu(var, cpu) (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]))
#define RELOC_HIDE(ptr, off)                    /
  ({ unsigned long __ptr;                   /
    __asm__ ("" : "=g"(__ptr) : "0"(ptr));      /
    (typeof(ptr)) (__ptr + (off)); })