Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=1169783085adb9ac969d21103a6885e8435f7ed3
Commit: 1169783085adb9ac969d21103a6885e8435f7ed3
Parent: 4a55b45036a677fac43fe81ddf7fdcd007aaaee7
Author: Peter Zijlstra <[EMAIL PROTECTED]>
AuthorDate: Wed Sep 5 14:32:49 2007 +0200
Committer: Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Wed Sep 5 14:32:49 2007 +0200
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 <[EMAIL PROTECTED]>
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
---
kernel/sched_fair.c | 38 ++++++++++++++++++++++----------------
1 files changed, 22 insertions(+), 16 deletions(-)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 2d01bbc..892616b 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));
}
/**************************************************
-
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