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    SubjectRe: [PATCH 05/16] sched: SCHED_DEADLINE policy implementation.
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    On Fri, 2012-04-06 at 09:14 +0200, Juri Lelli wrote:
    > +static
    > +int dl_runtime_exceeded(struct rq *rq, struct sched_dl_entity *dl_se)
    > +{
    > + int dmiss = dl_time_before(dl_se->deadline, rq->clock);
    > + int rorun = dl_se->runtime <= 0;
    >+
    > + if (!rorun && !dmiss)
    > + return 0;
    > +
    > + /*
    > + * If we are beyond our current deadline and we are still
    > + * executing, then we have already used some of the runtime of
    > + * the next instance. Thus, if we do not account that, we are
    > + * stealing bandwidth from the system at each deadline miss!
    > + */
    > + if (dmiss) {
    > + dl_se->runtime = rorun ? dl_se->runtime : 0;
    > + dl_se->runtime -= rq->clock - dl_se->deadline;
    > + }

    So ideally this can't happen, but since we already leak time from the
    system through means of hardirq / kstop / context-switch-overhead /
    clock-jitter etc.. we avoid the error accumulating?

    > +
    > + return 1;
    > +}




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