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프로세스를 그룹화하는 방법에 대한 설정

 CONFIG_CGROUP_SCHED    - 그룹화하는 방법으로 cgroup을 사용

 CONFIG_USER_SCHED         - 그룹화하는 방법으로 process의 UID를 사용

그룹 스케줄링 대상에 대한 설정

 CONFIG_FAIR_GROUP_SCHED  - normal process에 대한 그룹 스케줄링을 활성화

 CONFIG_RT_GROUP_SCHED     - real time process에 대한 그룹 스케줄링을 활성화

 static inline void context_switch(struct rq *rq, struct task_struct *prev, struct task_struct *next)
{
    struct mm_struct *mm, *oldmm;

    prepare_task_switch(rq, prev, next);
    trace_sched_switch(rq, prev, next);
    mm = next->mm;
    oldmm = prev->active_mm;
    /*
     * For paravirt, this is coupled with an exit in switch_to to
     * combine the page table reload and the switch backend into
     * one hypercall.
     */
    arch_start_context_switch(prev);

    if (unlikely(!mm)) {
        next->active_mm = oldmm;
        atomic_inc(&oldmm->mm_count);
        enter_lazy_tlb(oldmm, next);
    } else
        switch_mm(oldmm, mm, next);    // 프로세스 공간의 전환처리

    if (unlikely(!prev->mm)) {
        prev->active_mm = NULL;
        rq->prev_mm = oldmm;
    }
    /*
     * Since the runqueue lock will be released by the next
     * task (which is an invalid locking op but in the case
     * of the scheduler it's an obvious special-case), so we
     * do an early lockdep release here:
     */
#ifndef __ARCH_WANT_UNLOCKED_CTXSW
    spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
#endif

    /* Here we just switch the register state and the stack. */
    switch_to(prev, next, prev);         // 각종 레지스터의 전환처리

    barrier();
    /*
     * this_rq must be evaluated again because prev may have moved
     * CPUs since it called schedule(), thus the 'rq' on its stack
     * frame will be invalid.
     */
    finish_task_switch(this_rq(), prev);
}

 struct thread_info {
    struct task_struct  *task;                   /* main task structure */
    struct exec_domain  *exec_domain;   /* execution domain */
    __u32           flags;                          /* low level flags */
    __u32           status;                       /* thread synchronous flags */
    __u32           cpu;                         /* current CPU */
    int         preempt_count;               /* 0 => preemptable,
                           <0 => BUG */
    mm_segment_t        addr_limit;
    struct restart_block    restart_block;
    void __user     *sysenter_return;
#ifdef CONFIG_X86_32
    unsigned long           previous_esp;   /* ESP of the previous stack in case of nested (IRQ) stacks */       
    __u8            supervisor_stack[0];
#endif
    int         uaccess_err;
};

--------------arm-----------

/*
 * low level task data that entry.S needs immediate access to.
 * __switch_to() assumes cpu_context follows immediately after cpu_domain.
 */
struct thread_info {
    unsigned long       flags;             /* low level flags */                           8
    int         preempt_count;              /* 0 => preemptable, <0 => bug */       4
    mm_segment_t        addr_limit;     /* address limit */                            
    struct task_struct  *task;             /* main task structure */                     4
    struct exec_domain  *exec_domain;   /* execution domain */                 4
    __u32           cpu;                           /* cpu */                                     4
    __u32           cpu_domain;               /* cpu domain */                           4
    struct cpu_context_save cpu_context;    /* cpu context */
    __u32           syscall;                          /* syscall number */                  4
    __u8            used_cp[16];                  /* thread used copro */              1
    unsigned long       tp_value;                                                                8
    struct crunch_state crunchstate;              
    union fp_state      fpstate __attribute__((aligned(8)));
    union vfp_state     vfpstate;
#ifdef CONFIG_ARM_THUMBEE
    unsigned long       thumbee_state;  /* ThumbEE Handler Base register */
#endif
    struct restart_block    restart_block;
};