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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2007-09-05 14:32:49 +0200
committerIngo Molnar <mingo@elte.hu>2007-09-05 14:32:49 +0200
commit1169783085adb9ac969d21103a6885e8435f7ed3 (patch)
tree8d5313ef18ba821436aa838cb6f03f065049ef21 /kernel
parent4a55b45036a677fac43fe81ddf7fdcd007aaaee7 (diff)
downloadlinux-1169783085adb9ac969d21103a6885e8435f7ed3.tar.bz2
sched: fix ideal_runtime calculations for reniced tasks
fix ideal_runtime: - do not scale it using niced_granularity() it is against sum_exec_delta, so its wall-time, not fair-time. - move the whole check into __check_preempt_curr_fair() so that wakeup preemption can also benefit from the new logic. this also results in code size reduction: text data bss dec hex filename 13391 228 1204 14823 39e7 sched.o.before 13369 228 1204 14801 39d1 sched.o.after Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched_fair.c38
1 files changed, 22 insertions, 16 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 2d01bbc2d04a..892616bf2c77 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -678,11 +678,31 @@ __check_preempt_curr_fair(struct cfs_rq *cfs_rq, struct sched_entity *se,
struct sched_entity *curr, unsigned long granularity)
{
s64 __delta = curr->fair_key - se->fair_key;
+ unsigned long ideal_runtime, delta_exec;
+
+ /*
+ * ideal_runtime is compared against sum_exec_runtime, which is
+ * walltime, hence do not scale.
+ */
+ ideal_runtime = max(sysctl_sched_latency / cfs_rq->nr_running,
+ (unsigned long)sysctl_sched_min_granularity);
+
+ /*
+ * If we executed more than what the latency constraint suggests,
+ * reduce the rescheduling granularity. This way the total latency
+ * of how much a task is not scheduled converges to
+ * sysctl_sched_latency:
+ */
+ delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
+ if (delta_exec > ideal_runtime)
+ granularity = 0;
/*
* Take scheduling granularity into account - do not
* preempt the current task unless the best task has
* a larger than sched_granularity fairness advantage:
+ *
+ * scale granularity as key space is in fair_clock.
*/
if (__delta > niced_granularity(curr, granularity))
resched_task(rq_of(cfs_rq)->curr);
@@ -731,7 +751,6 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
{
- unsigned long gran, ideal_runtime, delta_exec;
struct sched_entity *next;
/*
@@ -748,21 +767,8 @@ static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
if (next == curr)
return;
- gran = sched_granularity(cfs_rq);
- ideal_runtime = niced_granularity(curr,
- max(sysctl_sched_latency / cfs_rq->nr_running,
- (unsigned long)sysctl_sched_min_granularity));
- /*
- * If we executed more than what the latency constraint suggests,
- * reduce the rescheduling granularity. This way the total latency
- * of how much a task is not scheduled converges to
- * sysctl_sched_latency:
- */
- delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
- if (delta_exec > ideal_runtime)
- gran = 0;
-
- __check_preempt_curr_fair(cfs_rq, next, curr, gran);
+ __check_preempt_curr_fair(cfs_rq, next, curr,
+ sched_granularity(cfs_rq));
}
/**************************************************