diff options
| author | Tianchen Ding <dtcccc@linux.alibaba.com> | 2024-06-26 10:35:05 +0800 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-07-29 12:22:35 +0200 |
| commit | faa42d29419def58d3c3e5b14ad4037f0af3b496 (patch) | |
| tree | c64603b96df19d2af66d6c47a2119e976a702117 /kernel | |
| parent | a58501fb8320d6232507f722b4c9dcd4e03362ee (diff) | |
| download | linux-faa42d29419def58d3c3e5b14ad4037f0af3b496.tar.gz linux-faa42d29419def58d3c3e5b14ad4037f0af3b496.zip | |
sched/fair: Make SCHED_IDLE entity be preempted in strict hierarchy
Consider the following cgroup:
root
|
------------------------
| |
normal_cgroup idle_cgroup
| |
SCHED_IDLE task_A SCHED_NORMAL task_B
According to the cgroup hierarchy, A should preempt B. But current
check_preempt_wakeup_fair() treats cgroup se and task separately, so B
will preempt A unexpectedly.
Unify the wakeup logic by {c,p}se_is_idle only. This makes SCHED_IDLE of
a task a relative policy that is effective only within its own cgroup,
similar to the behavior of NICE.
Also fix se_is_idle() definition when !CONFIG_FAIR_GROUP_SCHED.
Fixes: 304000390f88 ("sched: Cgroup SCHED_IDLE support")
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Don <joshdon@google.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20240626023505.1332596-1-dtcccc@linux.alibaba.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 22 |
1 files changed, 9 insertions, 13 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 02694fc5fce9..99c80abdbaaa 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -511,7 +511,7 @@ static int cfs_rq_is_idle(struct cfs_rq *cfs_rq) static int se_is_idle(struct sched_entity *se) { - return 0; + return task_has_idle_policy(task_of(se)); } #endif /* CONFIG_FAIR_GROUP_SCHED */ @@ -8381,16 +8381,7 @@ static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int if (test_tsk_need_resched(curr)) return; - /* Idle tasks are by definition preempted by non-idle tasks. */ - if (unlikely(task_has_idle_policy(curr)) && - likely(!task_has_idle_policy(p))) - goto preempt; - - /* - * Batch and idle tasks do not preempt non-idle tasks (their preemption - * is driven by the tick): - */ - if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION)) + if (!sched_feat(WAKEUP_PREEMPTION)) return; find_matching_se(&se, &pse); @@ -8400,7 +8391,7 @@ static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int pse_is_idle = se_is_idle(pse); /* - * Preempt an idle group in favor of a non-idle group (and don't preempt + * Preempt an idle entity in favor of a non-idle entity (and don't preempt * in the inverse case). */ if (cse_is_idle && !pse_is_idle) @@ -8408,9 +8399,14 @@ static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int if (cse_is_idle != pse_is_idle) return; + /* + * BATCH and IDLE tasks do not preempt others. + */ + if (unlikely(p->policy != SCHED_NORMAL)) + return; + cfs_rq = cfs_rq_of(se); update_curr(cfs_rq); - /* * XXX pick_eevdf(cfs_rq) != se ? */ |