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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2007-10-15 17:00:10 +0200
committerIngo Molnar <mingo@elte.hu>2007-10-15 17:00:10 +0200
commit67e9fb2a39a1d454218d50383094940982be138f (patch)
tree3b981b8d43d6c23f070df73033d731a6f00f0b0b /kernel
parent1aa4731eff7dab7bd01747b46f654f449f1cfc2c (diff)
sched: add vslice
add vslice: the load-dependent "virtual slice" a task should run ideally, so that the observed latency stays within the sched_latency window. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c2
-rw-r--r--kernel/sched_fair.c44
2 files changed, 31 insertions, 15 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 5004dff9185..fe1165b226a 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1615,6 +1615,7 @@ static void __sched_fork(struct task_struct *p)
p->se.exec_start = 0;
p->se.sum_exec_runtime = 0;
p->se.prev_sum_exec_runtime = 0;
+ p->se.last_min_vruntime = 0;
#ifdef CONFIG_SCHEDSTATS
p->se.wait_start = 0;
@@ -6495,6 +6496,7 @@ static inline void init_cfs_rq(struct cfs_rq *cfs_rq, struct rq *rq)
#ifdef CONFIG_FAIR_GROUP_SCHED
cfs_rq->rq = rq;
#endif
+ cfs_rq->min_vruntime = (u64)(-(1LL << 20));
}
void __init sched_init(void)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 5db7bd18e81..87acc5cedd2 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -243,6 +243,15 @@ static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
return period;
}
+static u64 __sched_vslice(unsigned long nr_running)
+{
+ u64 period = __sched_period(nr_running);
+
+ do_div(period, nr_running);
+
+ return period;
+}
+
/*
* Update the current task's runtime statistics. Skip current tasks that
* are not in our scheduling class.
@@ -441,32 +450,33 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
static void
place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
{
- u64 min_runtime, latency;
+ u64 vruntime;
- min_runtime = cfs_rq->min_vruntime;
+ vruntime = cfs_rq->min_vruntime;
if (sched_feat(USE_TREE_AVG)) {
struct sched_entity *last = __pick_last_entity(cfs_rq);
if (last) {
- min_runtime = __pick_next_entity(cfs_rq)->vruntime;
- min_runtime += last->vruntime;
- min_runtime >>= 1;
+ vruntime += last->vruntime;
+ vruntime >>= 1;
}
- } else if (sched_feat(APPROX_AVG))
- min_runtime += sysctl_sched_latency/2;
+ } else if (sched_feat(APPROX_AVG) && cfs_rq->nr_running)
+ vruntime += __sched_vslice(cfs_rq->nr_running)/2;
if (initial && sched_feat(START_DEBIT))
- min_runtime += sched_slice(cfs_rq, se);
+ vruntime += __sched_vslice(cfs_rq->nr_running + 1);
if (!initial && sched_feat(NEW_FAIR_SLEEPERS)) {
- latency = sysctl_sched_latency;
- if (min_runtime > latency)
- min_runtime -= latency;
+ s64 latency = cfs_rq->min_vruntime - se->last_min_vruntime;
+ if (latency < 0 || !cfs_rq->nr_running)
+ latency = 0;
else
- min_runtime = 0;
+ latency = min_t(s64, latency, sysctl_sched_latency);
+ vruntime -= latency;
}
- se->vruntime = max(se->vruntime, min_runtime);
+ se->vruntime = vruntime;
+
}
static void
@@ -478,6 +488,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
update_curr(cfs_rq);
if (wakeup) {
+ /* se->vruntime += cfs_rq->min_vruntime; */
place_entity(cfs_rq, se, 0);
enqueue_sleeper(cfs_rq, se);
}
@@ -492,8 +503,8 @@ static void
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
{
update_stats_dequeue(cfs_rq, se);
-#ifdef CONFIG_SCHEDSTATS
if (sleep) {
+#ifdef CONFIG_SCHEDSTATS
if (entity_is_task(se)) {
struct task_struct *tsk = task_of(se);
@@ -502,8 +513,11 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
if (tsk->state & TASK_UNINTERRUPTIBLE)
se->block_start = rq_of(cfs_rq)->clock;
}
- }
#endif
+ /* se->vruntime = entity_key(cfs_rq, se); */
+ se->last_min_vruntime = cfs_rq->min_vruntime;
+ }
+
if (se != cfs_rq->curr)
__dequeue_entity(cfs_rq, se);
account_entity_dequeue(cfs_rq, se);