Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=95938a35c5562afa7af7252821e44132391a3db8
Commit: 95938a35c5562afa7af7252821e44132391a3db8
Parent: ce6c131131df442f0d49d064129ecc52d9fe8ca9
Author: Mike Galbraith <[EMAIL PROTECTED]>
AuthorDate: Mon Oct 15 17:00:14 2007 +0200
Committer: Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Mon Oct 15 17:00:14 2007 +0200
sched: prevent wakeup over-scheduling
Prevent wakeup over-scheduling. Once a task has been preempted by a
task of the same or lower priority, it becomes ineligible for repeated
preemption by same until it has been ticked, or slept. Instead, the
task is marked for preemption at the next tick. Tasks of higher
priority still preempt immediately.
Signed-off-by: Mike Galbraith <[EMAIL PROTECTED]>
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
---
include/linux/sched.h | 1 +
kernel/sched.c | 4 +++-
kernel/sched_fair.c | 14 +++++++++++---
3 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 04233c8..8be5b57 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -912,6 +912,7 @@ struct sched_entity {
struct load_weight load; /* for load-balancing */
struct rb_node run_node;
unsigned int on_rq;
+ int peer_preempt;
u64 exec_start;
u64 sum_exec_runtime;
diff --git a/kernel/sched.c b/kernel/sched.c
index 0bd8f2c..e8051bd 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -445,6 +445,7 @@ enum {
SCHED_FEAT_TREE_AVG = 4,
SCHED_FEAT_APPROX_AVG = 8,
SCHED_FEAT_WAKEUP_PREEMPT = 16,
+ SCHED_FEAT_PREEMPT_RESTRICT = 32,
};
const_debug unsigned int sysctl_sched_features =
@@ -452,7 +453,8 @@ const_debug unsigned int sysctl_sched_features =
SCHED_FEAT_START_DEBIT *1 |
SCHED_FEAT_TREE_AVG *0 |
SCHED_FEAT_APPROX_AVG *0 |
- SCHED_FEAT_WAKEUP_PREEMPT *1;
+ SCHED_FEAT_WAKEUP_PREEMPT *1 |
+ SCHED_FEAT_PREEMPT_RESTRICT *1;
#define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 3843ec7..f819f94 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -526,6 +526,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity
*se, int sleep)
update_stats_dequeue(cfs_rq, se);
if (sleep) {
+ se->peer_preempt = 0;
#ifdef CONFIG_SCHEDSTATS
if (entity_is_task(se)) {
struct task_struct *tsk = task_of(se);
@@ -553,8 +554,10 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct
sched_entity *curr)
ideal_runtime = sched_slice(cfs_rq, curr);
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
- if (delta_exec > ideal_runtime)
+ if (delta_exec > ideal_runtime ||
+ (sched_feat(PREEMPT_RESTRICT) && curr->peer_preempt))
resched_task(rq_of(cfs_rq)->curr);
+ curr->peer_preempt = 0;
}
static void
@@ -839,8 +842,12 @@ static void check_preempt_wakeup(struct rq *rq, struct
task_struct *p)
if (unlikely(se->load.weight != NICE_0_LOAD))
gran = calc_delta_fair(gran, &se->load);
- if (delta > gran)
- resched_task(curr);
+ if (delta > gran) {
+ int now = !sched_feat(PREEMPT_RESTRICT);
+
+ if (now || p->prio < curr->prio || !se->peer_preempt++)
+ resched_task(curr);
+ }
}
}
@@ -1034,6 +1041,7 @@ static void task_new_fair(struct rq *rq, struct
task_struct *p)
check_spread(cfs_rq, curr);
__enqueue_entity(cfs_rq, se);
account_entity_enqueue(cfs_rq, se);
+ se->peer_preempt = 0;
resched_task(rq->curr);
}
-
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