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    Subject[PATCH 06/14] sched: add period support for -deadline tasks.
    Date
    From: Harald Gustafsson <harald.gustafsson@ericsson.com>

    Make it possible to specify a period (different or equal than
    deadline) for -deadline tasks.

    Signed-off-by: Harald Gustafsson <harald.gustafsson@ericsson.com>
    Signed-off-by: Dario Faggioli <raistlin@linux.it>
    Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
    ---
    include/linux/sched.h | 1 +
    kernel/sched/core.c | 15 ++++++++++++---
    kernel/sched/deadline.c | 10 +++++++---
    3 files changed, 20 insertions(+), 6 deletions(-)

    diff --git a/include/linux/sched.h b/include/linux/sched.h
    index ff12481..4bfda68 100644
    --- a/include/linux/sched.h
    +++ b/include/linux/sched.h
    @@ -1284,6 +1284,7 @@ struct sched_dl_entity {
    */
    u64 dl_runtime; /* maximum runtime for each instance */
    u64 dl_deadline; /* relative deadline of each instance */
    + u64 dl_period; /* separation of two instances (period) */

    /*
    * Actual scheduling parameters. Initialized with the values above,
    diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    index d19235f..17a60e4 100644
    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -1570,6 +1570,7 @@ static void __sched_fork(struct task_struct *p)
    hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    p->dl.dl_runtime = p->dl.runtime = 0;
    p->dl.dl_deadline = p->dl.deadline = 0;
    + p->dl.dl_period = 0;
    p->dl.flags = 0;

    INIT_LIST_HEAD(&p->rt.run_list);
    @@ -3795,6 +3796,10 @@ __setparam_dl(struct task_struct *p, const struct sched_param2 *param2)
    init_dl_task_timer(dl_se);
    dl_se->dl_runtime = param2->sched_runtime;
    dl_se->dl_deadline = param2->sched_deadline;
    + if (param2->sched_period != 0)
    + dl_se->dl_period = param2->sched_period;
    + else
    + dl_se->dl_period = dl_se->dl_deadline;
    dl_se->flags = param2->sched_flags;
    dl_se->dl_throttled = 0;
    dl_se->dl_new = 1;
    @@ -3808,19 +3813,23 @@ __getparam_dl(struct task_struct *p, struct sched_param2 *param2)
    param2->sched_priority = p->rt_priority;
    param2->sched_runtime = dl_se->dl_runtime;
    param2->sched_deadline = dl_se->dl_deadline;
    + param2->sched_period = dl_se->dl_period;
    param2->sched_flags = dl_se->flags;
    }

    /*
    * This function validates the new parameters of a -deadline task.
    * We ask for the deadline not being zero, and greater or equal
    - * than the runtime.
    + * than the runtime, as well as the period of being zero or
    + * greater than deadline.
    */
    static bool
    __checkparam_dl(const struct sched_param2 *prm)
    {
    - return prm && (&prm->sched_deadline) != 0 &&
    - (s64)(&prm->sched_deadline - &prm->sched_runtime) >= 0;
    + return prm && prm->sched_deadline != 0 &&
    + (prm->sched_period == 0 ||
    + (s64)(prm->sched_period - prm->sched_deadline) >= 0) &&
    + (s64)(prm->sched_deadline - prm->sched_runtime) >= 0;
    }

    /*
    diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
    index d3334fc..92546f3 100644
    --- a/kernel/sched/deadline.c
    +++ b/kernel/sched/deadline.c
    @@ -287,7 +287,7 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
    * arbitrary large.
    */
    while (dl_se->runtime <= 0) {
    - dl_se->deadline += dl_se->dl_deadline;
    + dl_se->deadline += dl_se->dl_period;
    dl_se->runtime += dl_se->dl_runtime;
    }

    @@ -327,9 +327,13 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
    *
    * This function returns true if:
    *
    - * runtime / (deadline - t) > dl_runtime / dl_deadline ,
    + * runtime / (deadline - t) > dl_runtime / dl_period ,
    *
    * IOW we can't recycle current parameters.
    + *
    + * Notice that the bandwidth check is done against the period. For
    + * task with deadline equal to period this is the same of using
    + * dl_deadline instead of dl_period in the equation above.
    */
    static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t)
    {
    @@ -353,7 +357,7 @@ static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t)
    * of anything below microseconds resolution is actually fiction
    * (but still we want to give the user that illusion >;).
    */
    - left = (dl_se->dl_deadline >> 10) * (dl_se->runtime >> 10);
    + left = (dl_se->dl_period >> 10) * (dl_se->runtime >> 10);
    right = ((dl_se->deadline - t) >> 10) * (dl_se->dl_runtime >> 10);

    return dl_time_before(right, left);
    --
    1.7.9.5


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