diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2019-04-23 16:26:36 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-06-03 11:49:37 +0200 |
| commit | 3bd3706251ee8ab67e69d9340ac2abdca217e733 (patch) | |
| tree | 4431aa630d095905d840ace6a0b86e266395f71a /kernel/sched/cpupri.c | |
| parent | f2c7c76c5d0a443053e94adb9f0918fa2fb85c3a (diff) | |
sched/core: Provide a pointer to the valid CPU mask
In commit:
4b53a3412d66 ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper")
the tsk_nr_cpus_allowed() wrapper was removed. There was not
much difference in !RT but in RT we used this to implement
migrate_disable(). Within a migrate_disable() section the CPU mask is
restricted to single CPU while the "normal" CPU mask remains untouched.
As an alternative implementation Ingo suggested to use:
struct task_struct {
const cpumask_t *cpus_ptr;
cpumask_t cpus_mask;
};
with
t->cpus_ptr = &t->cpus_mask;
In -RT we then can switch the cpus_ptr to:
t->cpus_ptr = &cpumask_of(task_cpu(p));
in a migration disabled region. The rules are simple:
- Code that 'uses' ->cpus_allowed would use the pointer.
- Code that 'modifies' ->cpus_allowed would use the direct mask.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/cpupri.c')
| -rw-r--r-- | kernel/sched/cpupri.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c index daaadf939ccb..f7d2c10b4c92 100644 --- a/kernel/sched/cpupri.c +++ b/kernel/sched/cpupri.c @@ -98,11 +98,11 @@ int cpupri_find(struct cpupri *cp, struct task_struct *p, if (skip) continue; - if (cpumask_any_and(&p->cpus_allowed, vec->mask) >= nr_cpu_ids) + if (cpumask_any_and(p->cpus_ptr, vec->mask) >= nr_cpu_ids) continue; if (lowest_mask) { - cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask); + cpumask_and(lowest_mask, p->cpus_ptr, vec->mask); /* * We have to ensure that we have at least one bit |