diff options
| author |   Will Deacon <will@kernel.org> | 2021-07-30 12:24:31 +0100 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2021-08-20 12:32:59 +0200 |
| commit | 97c0054dbe2c3c59d1156fd233f2d44e91981c8e (patch) | |
| tree | fe236eb64fc7760d430b8b2272ffb10f222efa79 | |
| parent | cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() (diff) | |
| download | linux-dev-97c0054dbe2c3c59d1156fd233f2d44e91981c8e.tar.xz linux-dev-97c0054dbe2c3c59d1156fd233f2d44e91981c8e.zip | |
cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq()
select_fallback_rq() only needs to recheck for an allowed CPU if the
affinity mask of the task has changed since the last check.
Return a 'bool' from cpuset_cpus_allowed_fallback() to indicate whether
the affinity mask was updated, and use this to elide the allowed check
when the mask has been left alone.
No functional change.
Suggested-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lore.kernel.org/r/20210730112443.23245-5-will@kernel.org
| -rw-r--r-- | include/linux/cpuset.h | 5 | ||||
| -rw-r--r-- | kernel/cgroup/cpuset.c | 10 | ||||
| -rw-r--r-- | kernel/sched/core.c | 3 |
3 files changed, 12 insertions, 6 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 414a8e694413..d2b9c41c8edf 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -59,7 +59,7 @@ extern void cpuset_wait_for_hotplug(void); extern void cpuset_read_lock(void); extern void cpuset_read_unlock(void); extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask); -extern void cpuset_cpus_allowed_fallback(struct task_struct *p); +extern bool cpuset_cpus_allowed_fallback(struct task_struct *p); extern nodemask_t cpuset_mems_allowed(struct task_struct *p); #define cpuset_current_mems_allowed (current->mems_allowed) void cpuset_init_current_mems_allowed(void); @@ -188,8 +188,9 @@ static inline void cpuset_cpus_allowed(struct task_struct *p, cpumask_copy(mask, task_cpu_possible_mask(p)); } -static inline void cpuset_cpus_allowed_fallback(struct task_struct *p) +static inline bool cpuset_cpus_allowed_fallback(struct task_struct *p) { + return false; } static inline nodemask_t cpuset_mems_allowed(struct task_struct *p) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 391813245cb2..6500cbe0ce16 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -3327,17 +3327,22 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) * which will not contain a sane cpumask during cases such as cpu hotplugging. * This is the absolute last resort for the scheduler and it is only used if * _every_ other avenue has been traveled. + * + * Returns true if the affinity of @tsk was changed, false otherwise. **/ -void cpuset_cpus_allowed_fallback(struct task_struct *tsk) +bool cpuset_cpus_allowed_fallback(struct task_struct *tsk) { const struct cpumask *possible_mask = task_cpu_possible_mask(tsk); const struct cpumask *cs_mask; + bool changed = false; rcu_read_lock(); cs_mask = task_cs(tsk)->cpus_allowed; - if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask)) + if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask)) { do_set_cpus_allowed(tsk, cs_mask); + changed = true; + } rcu_read_unlock(); /* @@ -3357,6 +3362,7 @@ void cpuset_cpus_allowed_fallback(struct task_struct *tsk) * select_fallback_rq() will fix things ups and set cpu_possible_mask * if required. */ + return changed; } void __init cpuset_init_current_mems_allowed(void) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 6f31267c4beb..b9d4bae922a8 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3141,8 +3141,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p) /* No more Mr. Nice Guy. */ switch (state) { case cpuset: - if (IS_ENABLED(CONFIG_CPUSETS)) { - cpuset_cpus_allowed_fallback(p); + if (cpuset_cpus_allowed_fallback(p)) { state = possible; break; } |