[git pull] scheduler fixes

Ingo Molnar
2008-03-15T01:48:01Z

Linus, please pull the latest scheduler fixes git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-devel.git for-linus

this fixes a number of bugs and regressions. Thanks,

Ingo

------------------>
Hiroshi Shimamoto (1):
sched: fix race in schedule()

Ingo Molnar (4):
sched: fix update_load_add()/sub()
sched: fix calc_delta_mine()
sched: fix fair sleepers
sched: simplify sched_slice()

Peter Zijlstra (2):
sched: min_vruntime fix
sched: fix overload performance: buddy wakeups

kernel/sched.c | 44 ++++++++++++--------------
kernel/sched_fair.c | 86 +++++++++++++++++++++++++++++++++++---------------
2 files changed, 80 insertions(+), 50 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 1cb53fb..d1ad69b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -301,7 +301,7 @@ struct cfs_rq {
/* 'curr' points to currently running entity on this cfs_rq.
* It is set to NULL otherwise (i.e when none are currently running).
*/
- struct sched_entity *curr;
+ struct sched_entity *curr, *next;

unsigned long nr_spread_over;

@@ -1084,7 +1084,7 @@ calc_delta_mine(unsigned long delta_exec, unsigned long weight,
u64 tmp;

if (unlikely(!lw->inv_weight))
- lw->inv_weight = (WMULT_CONST - lw->weight/2) / lw->weight + 1;
+ lw->inv_weight = (WMULT_CONST-lw->weight/2) / (lw->weight+1);

tmp = (u64)delta_exec * weight;
/*
@@ -1108,11 +1108,13 @@ calc_delta_fair(unsigned long delta_exec, struct load_weight *lw)
static inline void update_load_add(struct load_weight *lw, unsigned long inc)
{
lw->weight += inc;
+ lw->inv_weight = 0;
}

static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
{
lw->weight -= dec;
+ lw->inv_weight = 0;
}

/*
@@ -4268,11 +4270,10 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
oldprio = p->prio;
on_rq = p->se.on_rq;
running = task_current(rq, p);
- if (on_rq) {
+ if (on_rq)
dequeue_task(rq, p, 0);
- if (running)
- p->sched_class->put_prev_task(rq, p);
- }
+ if (running)
+ p->sched_class->put_prev_task(rq, p);

if (rt_prio(prio))
p->sched_class = &rt_sched_class;
@@ -4281,10 +4282,9 @@ void rt_mutex_setprio(struct task_struct *p, int prio)

p->prio = prio;

+ if (running)
+ p->sched_class->set_curr_task(rq);
if (on_rq) {
- if (running)
- p->sched_class->set_curr_task(rq);
-
enqueue_task(rq, p, 0);

check_class_changed(rq, p, prev_class, oldprio, running);
@@ -4581,19 +4581,17 @@ recheck:
update_rq_clock(rq);
on_rq = p->se.on_rq;
running = task_current(rq, p);
- if (on_rq) {
+ if (on_rq)
deactivate_task(rq, p, 0);
- if (running)
- p->sched_class->put_prev_task(rq, p);
- }
+ if (running)
+ p->sched_class->put_prev_task(rq, p);

oldprio = p->prio;
__setscheduler(rq, p, policy, param->sched_priority);

+ if (running)
+ p->sched_class->set_curr_task(rq);
if (on_rq) {
- if (running)
- p->sched_class->set_curr_task(rq);
-
activate_task(rq, p, 0);

check_class_changed(rq, p, prev_class, oldprio, running);
@@ -7618,11 +7616,10 @@ void sched_move_task(struct task_struct *tsk)
running = task_current(rq, tsk);
on_rq = tsk->se.on_rq;

- if (on_rq) {
+ if (on_rq)
dequeue_task(rq, tsk, 0);
- if (unlikely(running))
- tsk->sched_class->put_prev_task(rq, tsk);
- }
+ if (unlikely(running))
+ tsk->sched_class->put_prev_task(rq, tsk);

set_task_rq(tsk, task_cpu(tsk));

@@ -7631,11 +7628,10 @@ void sched_move_task(struct task_struct *tsk)
tsk->sched_class->moved_group(tsk);
#endif

- if (on_rq) {
- if (unlikely(running))
- tsk->sched_class->set_curr_task(rq);
+ if (unlikely(running))
+ tsk->sched_class->set_curr_task(rq);
+ if (on_rq)
enqueue_task(rq, tsk, 0);
- }

task_rq_unlock(rq, &flags);
}
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index e2a5305..f2cc590 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -175,8 +175,15 @@ static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
* Maintain a cache of leftmost tree entries (it is frequently
* used):
*/
- if (leftmost)
+ if (leftmost) {
cfs_rq->rb_leftmost = &se->run_node;
+ /*
+ * maintain cfs_rq->min_vruntime to be a monotonic increasing
+ * value tracking the leftmost vruntime in the tree.
+ */
+ cfs_rq->min_vruntime =
+ max_vruntime(cfs_rq->min_vruntime, se->vruntime);
+ }

rb_link_node(&se->run_node, parent, link);
rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
@@ -184,8 +191,24 @@ static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)

static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- if (cfs_rq->rb_leftmost == &se->run_node)
- cfs_rq->rb_leftmost = rb_next(&se->run_node);
+ if (cfs_rq->rb_leftmost == &se->run_node) {
+ struct rb_node *next_node;
+ struct sched_entity *next;
+
+ next_node = rb_next(&se->run_node);
+ cfs_rq->rb_leftmost = next_node;
+
+ if (next_node) {
+ next = rb_entry(next_node,
+ struct sched_entity, run_node);
+ cfs_rq->min_vruntime =
+ max_vruntime(cfs_rq->min_vruntime,
+ next->vruntime);
+ }
+ }
+
+ if (cfs_rq->next == se)
+ cfs_rq->next = NULL;

rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
}
@@ -260,12 +283,8 @@ static u64 __sched_period(unsigned long nr_running)
*/
static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- u64 slice = __sched_period(cfs_rq->nr_running);
-
- slice *= se->load.weight;
- do_div(slice, cfs_rq->load.weight);
-
- return slice;
+ return calc_delta_mine(__sched_period(cfs_rq->nr_running),
+ se->load.weight, &cfs_rq->load);
}

/*
@@ -303,7 +322,6 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
unsigned long delta_exec)
{
unsigned long delta_exec_weighted;
- u64 vruntime;

schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));

@@ -315,19 +333,6 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
&curr->load);
}
curr->vruntime += delta_exec_weighted;
-
- /*
- * maintain cfs_rq->min_vruntime to be a monotonic increasing
- * value tracking the leftmost vruntime in the tree.
- */
- if (first_fair(cfs_rq)) {
- vruntime = min_vruntime(curr->vruntime,
- __pick_next_entity(cfs_rq)->vruntime);
- } else
- vruntime = curr->vruntime;
-
- cfs_rq->min_vruntime =
- max_vruntime(cfs_rq->min_vruntime, vruntime);
}

static void update_curr(struct cfs_rq *cfs_rq)
@@ -493,7 +498,11 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
{
u64 vruntime;

- vruntime = cfs_rq->min_vruntime;
+ if (first_fair(cfs_rq)) {
+ vruntime = min_vruntime(cfs_rq->min_vruntime,
+ __pick_next_entity(cfs_rq)->vruntime);
+ } else
+ vruntime = cfs_rq->min_vruntime;

if (sched_feat(TREE_AVG)) {
struct sched_entity *last = __pick_last_entity(cfs_rq);
@@ -515,8 +524,10 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)

if (!initial) {
/* sleeps upto a single latency don't count. */
- if (sched_feat(NEW_FAIR_SLEEPERS))
- vruntime -= sysctl_sched_latency;
+ if (sched_feat(NEW_FAIR_SLEEPERS)) {
+ vruntime -= calc_delta_fair(sysctl_sched_latency,
+ &cfs_rq->load);
+ }

/* ensure we never gain time by being placed backwards. */
vruntime = max_vruntime(se->vruntime, vruntime);
@@ -616,12 +627,32 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
se->prev_sum_exec_runtime = se->sum_exec_runtime;
}

+static struct sched_entity *
+pick_next(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ s64 diff, gran;
+
+ if (!cfs_rq->next)
+ return se;
+
+ diff = cfs_rq->next->vruntime - se->vruntime;
+ if (diff < 0)
+ return se;
+
+ gran = calc_delta_fair(sysctl_sched_wakeup_granularity, &cfs_rq->load);
+ if (diff > gran)
+ return se;
+
+ return cfs_rq->next;
+}
+
static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
{
struct sched_entity *se = NULL;

if (first_fair(cfs_rq)) {
se = __pick_next_entity(cfs_rq);
+ se = pick_next(cfs_rq, se);
set_next_entity(cfs_rq, se);
}

@@ -1060,6 +1091,9 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
resched_task(curr);
return;
}
+
+ cfs_rq_of(pse)->next = pse;
+
/*
* Batch tasks do not preempt (their preemption is driven by