diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-01-15 14:53:38 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-02-20 14:40:20 -0800 |
| commit | df94b12439ca449a852e579fc2952dac80f70c90 (patch) | |
| tree | f9912dc93377361a20bc05a76ccb904c70e48804 /kernel | |
| parent | 2cf155b300c4839a7238b825c7c5f417e9d7cc68 (diff) | |
sched: SCHED_OTHER vs SCHED_IDLE isolation
commit 6bc912b71b6f33b041cfde93ca3f019cbaa852bc upstream.
Stronger SCHED_IDLE isolation:
- no SCHED_IDLE buddies
- never let SCHED_IDLE preempt on wakeup
- always preempt SCHED_IDLE on wakeup
- limit SLEEPER fairness for SCHED_IDLE.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched_fair.c | 30 |
1 files changed, 22 insertions, 8 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 06a68c4b0db..c91973d8b37 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -681,9 +681,13 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) unsigned long thresh = sysctl_sched_latency; /* - * convert the sleeper threshold into virtual time + * Convert the sleeper threshold into virtual time. + * SCHED_IDLE is a special sub-class. We care about + * fairness only relative to other SCHED_IDLE tasks, + * all of which have the same weight. */ - if (sched_feat(NORMALIZED_SLEEPER)) + if (sched_feat(NORMALIZED_SLEEPER) && + task_of(se)->policy != SCHED_IDLE) thresh = calc_delta_fair(thresh, se); vruntime -= thresh; @@ -1328,14 +1332,18 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) static void set_last_buddy(struct sched_entity *se) { - for_each_sched_entity(se) - cfs_rq_of(se)->last = se; + if (likely(task_of(se)->policy != SCHED_IDLE)) { + for_each_sched_entity(se) + cfs_rq_of(se)->last = se; + } } static void set_next_buddy(struct sched_entity *se) { - for_each_sched_entity(se) - cfs_rq_of(se)->next = se; + if (likely(task_of(se)->policy != SCHED_IDLE)) { + for_each_sched_entity(se) + cfs_rq_of(se)->next = se; + } } /* @@ -1382,12 +1390,18 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync) return; /* - * Batch tasks do not preempt (their preemption is driven by + * Batch and idle tasks do not preempt (their preemption is driven by * the tick): */ - if (unlikely(p->policy == SCHED_BATCH)) + if (unlikely(p->policy != SCHED_NORMAL)) return; + /* Idle tasks are by definition preempted by everybody. */ + if (unlikely(curr->policy == SCHED_IDLE)) { + resched_task(curr); + return; + } + if (!sched_feat(WAKEUP_PREEMPT)) return; |