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| author | Qais Yousef <qais.yousef@arm.com> | 2020-03-02 13:27:18 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-03-06 12:57:27 +0100 |
| commit | a1bd02e1f28b1939cac8c64072a0e578c3cbc345 (patch) | |
| tree | b297a940228a68fadde6e97d77f078d3da1e8753 /kernel/sched | |
| parent | b28bc1e002c23ff8a4999c4a2fb1d4d412bc6f5e (diff) | |
| download | linux-a1bd02e1f28b1939cac8c64072a0e578c3cbc345.tar.gz linux-a1bd02e1f28b1939cac8c64072a0e578c3cbc345.tar.bz2 linux-a1bd02e1f28b1939cac8c64072a0e578c3cbc345.zip | |
sched/rt: Optimize cpupri_find() on non-heterogenous systems
By introducing a new cpupri_find_fitness() function that takes the
fitness_fn as an argument and only called when asym_system static key is
enabled.
cpupri_find() is now a wrapper function that calls cpupri_find_fitness()
passing NULL as a fitness_fn, hence disabling the logic that handles
fitness by default.
LINK: https://lore.kernel.org/lkml/c0772fca-0a4b-c88d-fdf2-5715fcf8447b@arm.com/
Reported-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fixes: 804d402fb6f6 ("sched/rt: Make RT capacity-aware")
Link: https://lkml.kernel.org/r/20200302132721.8353-4-qais.yousef@arm.com
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/cpupri.c | 10 | ||||
| -rw-r--r-- | kernel/sched/cpupri.h | 6 | ||||
| -rw-r--r-- | kernel/sched/rt.c | 23 |
3 files changed, 31 insertions, 8 deletions
diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c index 1bcfa1995550..dd3f16d1a04a 100644 --- a/kernel/sched/cpupri.c +++ b/kernel/sched/cpupri.c @@ -94,8 +94,14 @@ static inline int __cpupri_find(struct cpupri *cp, struct task_struct *p, return 1; } +int cpupri_find(struct cpupri *cp, struct task_struct *p, + struct cpumask *lowest_mask) +{ + return cpupri_find_fitness(cp, p, lowest_mask, NULL); +} + /** - * cpupri_find - find the best (lowest-pri) CPU in the system + * cpupri_find_fitness - find the best (lowest-pri) CPU in the system * @cp: The cpupri context * @p: The task * @lowest_mask: A mask to fill in with selected CPUs (or NULL) @@ -111,7 +117,7 @@ static inline int __cpupri_find(struct cpupri *cp, struct task_struct *p, * * Return: (int)bool - CPUs were found */ -int cpupri_find(struct cpupri *cp, struct task_struct *p, +int cpupri_find_fitness(struct cpupri *cp, struct task_struct *p, struct cpumask *lowest_mask, bool (*fitness_fn)(struct task_struct *p, int cpu)) { diff --git a/kernel/sched/cpupri.h b/kernel/sched/cpupri.h index 32dd520db11f..efbb492bb94c 100644 --- a/kernel/sched/cpupri.h +++ b/kernel/sched/cpupri.h @@ -19,8 +19,10 @@ struct cpupri { #ifdef CONFIG_SMP int cpupri_find(struct cpupri *cp, struct task_struct *p, - struct cpumask *lowest_mask, - bool (*fitness_fn)(struct task_struct *p, int cpu)); + struct cpumask *lowest_mask); +int cpupri_find_fitness(struct cpupri *cp, struct task_struct *p, + struct cpumask *lowest_mask, + bool (*fitness_fn)(struct task_struct *p, int cpu)); void cpupri_set(struct cpupri *cp, int cpu, int pri); int cpupri_init(struct cpupri *cp); void cpupri_cleanup(struct cpupri *cp); diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index f0071fa01c1d..29a86959bda4 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1504,7 +1504,7 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p) * let's hope p can move out. */ if (rq->curr->nr_cpus_allowed == 1 || - !cpupri_find(&rq->rd->cpupri, rq->curr, NULL, NULL)) + !cpupri_find(&rq->rd->cpupri, rq->curr, NULL)) return; /* @@ -1512,7 +1512,7 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p) * see if it is pushed or pulled somewhere else. */ if (p->nr_cpus_allowed != 1 && - cpupri_find(&rq->rd->cpupri, p, NULL, NULL)) + cpupri_find(&rq->rd->cpupri, p, NULL)) return; /* @@ -1691,6 +1691,7 @@ static int find_lowest_rq(struct task_struct *task) struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask); int this_cpu = smp_processor_id(); int cpu = task_cpu(task); + int ret; /* Make sure the mask is initialized first */ if (unlikely(!lowest_mask)) @@ -1699,8 +1700,22 @@ static int find_lowest_rq(struct task_struct *task) if (task->nr_cpus_allowed == 1) return -1; /* No other targets possible */ - if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask, - rt_task_fits_capacity)) + /* + * If we're on asym system ensure we consider the different capacities + * of the CPUs when searching for the lowest_mask. + */ + if (static_branch_unlikely(&sched_asym_cpucapacity)) { + + ret = cpupri_find_fitness(&task_rq(task)->rd->cpupri, + task, lowest_mask, + rt_task_fits_capacity); + } else { + + ret = cpupri_find(&task_rq(task)->rd->cpupri, + task, lowest_mask); + } + + if (!ret) return -1; /* No targets found */ /* |