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sched/deadline: Use sched_dl_entity's dl_density in dl_task_fits_capacity()

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Save a multiplication in dl_task_fits_capacity() by using already
maintained per-sched_dl_entity (i.e. per-task) `dl_runtime/dl_deadline`
(dl_density).

  cap_scale(dl_deadline, cap) >= dl_runtime

  dl_deadline * cap >> SCHED_CAPACITY_SHIFT >= dl_runtime

  cap >= dl_runtime << SCHED_CAPACITY_SHIFT / dl_deadline

  cap >= (dl_runtime << BW_SHIFT / dl_deadline) >>
				BW_SHIFT - SCHED_CAPACITY_SHIFT

  cap >= dl_density >> BW_SHIFT - SCHED_CAPACITY_SHIFT

__sched_setscheduler()->__checkparam_dl() ensures that the 2 corner
cases (if conditions) `runtime == RUNTIME_INF (-1)` and `period == 0`
of to_ratio(deadline, runtime) are not met when setting dl_density in
__sched_setscheduler()-> __setscheduler_params()->__setparam_dl().

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20220729111305.1275158-4-dietmar.eggemann@arm.com
This commit is contained in:
Dietmar Eggemann 2022-07-29 13:13:05 +02:00 committed by Ingo Molnar
parent 6092478bcb
commit b3f53daacc
1 changed files with 15 additions and 15 deletions
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30
kernel/sched/sched.h
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@ -320,21 +320,6 @@ struct dl_bw {
u64 total_bw;
};
/*
* Verify the fitness of task @p to run on @cpu taking into account the
* CPU original capacity and the runtime/deadline ratio of the task.
*
* The function will return true if the CPU original capacity of the
* @cpu scaled by SCHED_CAPACITY_SCALE >= runtime/deadline ratio of the
* task and false otherwise.
*/
static inline bool dl_task_fits_capacity(struct task_struct *p, int cpu)
{
unsigned long cap = arch_scale_cpu_capacity(cpu);
return cap_scale(p->dl.dl_deadline, cap) >= p->dl.dl_runtime;
}
extern void init_dl_bw(struct dl_bw *dl_b);
extern int sched_dl_global_validate(void);
extern void sched_dl_do_global(void);
@ -2899,6 +2884,21 @@ unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
enum cpu_util_type type,
struct task_struct *p);
/*
* Verify the fitness of task @p to run on @cpu taking into account the
* CPU original capacity and the runtime/deadline ratio of the task.
*
* The function will return true if the original capacity of @cpu is
* greater than or equal to task's deadline density right shifted by
* (BW_SHIFT - SCHED_CAPACITY_SHIFT) and false otherwise.
*/
static inline bool dl_task_fits_capacity(struct task_struct *p, int cpu)
{
unsigned long cap = arch_scale_cpu_capacity(cpu);
return cap >= p->dl.dl_density >> (BW_SHIFT - SCHED_CAPACITY_SHIFT);
}
static inline unsigned long cpu_bw_dl(struct rq *rq)
{
return (rq->dl.running_bw * SCHED_CAPACITY_SCALE) >> BW_SHIFT;