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    Subject[PATCH] sched/rt: Make update_curr_rt() more accurate
    Date
    rq->clock_task may be updated between the two calls of 
    rq_clock_task() in update_curr_rt(). Calling rq_clock_task() only
    once makes it more accurate and efficient, taking update_curr() as
    reference.

    Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
    Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
    ---
    kernel/sched/rt.c | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
    index 4056c19..d6d2a65 100644
    --- a/kernel/sched/rt.c
    +++ b/kernel/sched/rt.c
    @@ -950,12 +950,13 @@ static void update_curr_rt(struct rq *rq)
    {
    struct task_struct *curr = rq->curr;
    struct sched_rt_entity *rt_se = &curr->rt;
    + u64 now = rq_clock_task(rq);
    u64 delta_exec;

    if (curr->sched_class != &rt_sched_class)
    return;

    - delta_exec = rq_clock_task(rq) - curr->se.exec_start;
    + delta_exec = now - curr->se.exec_start;
    if (unlikely((s64)delta_exec <= 0))
    return;

    @@ -968,7 +969,7 @@ static void update_curr_rt(struct rq *rq)
    curr->se.sum_exec_runtime += delta_exec;
    account_group_exec_runtime(curr, delta_exec);

    - curr->se.exec_start = rq_clock_task(rq);
    + curr->se.exec_start = now;
    cgroup_account_cputime(curr, delta_exec);

    sched_rt_avg_update(rq, delta_exec);
    --
    1.9.1
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