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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2007-11-09 22:39:37 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2007-11-09 22:39:37 +0100 |
| commit | 2cb8600e6be4281e381d39e44de4359e46333e23 (patch) | |
| tree | 3ba87a4da52bdb2e082f8c459c6d39180f4e3f2c | |
| parent | 10b777246c6953100099af1870d35c8b24d49b12 (diff) | |
| download | lwn-2cb8600e6be4281e381d39e44de4359e46333e23.tar.gz lwn-2cb8600e6be4281e381d39e44de4359e46333e23.zip | |
sched: documentation: place_entity() comments
Add a few comments to place_entity(). No code changed.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | kernel/sched_fair.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 62b057603f07..8763bee6b661 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -473,19 +473,26 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) } else if (sched_feat(APPROX_AVG) && cfs_rq->nr_running) vruntime += sched_vslice(cfs_rq)/2; + /* + * The 'current' period is already promised to the current tasks, + * however the extra weight of the new task will slow them down a + * little, place the new task so that it fits in the slot that + * stays open at the end. + */ if (initial && sched_feat(START_DEBIT)) vruntime += sched_vslice_add(cfs_rq, se); if (!initial) { + /* sleeps upto a single latency don't count. */ if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se) && task_of(se)->policy != SCHED_BATCH) vruntime -= sysctl_sched_latency; - vruntime = max_t(s64, vruntime, se->vruntime); + /* ensure we never gain time by being placed backwards. */ + vruntime = max_vruntime(se->vruntime, vruntime); } se->vruntime = vruntime; - } static void |