Messages in this thread Patch in this message | | | Date | Wed, 31 Oct 2007 22:10:36 +0100 | From | Peter Zijlstra <> | Subject | [PATCH 6/6] sched: place_entity() comments |
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Add a few comments to place_entity().
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- kernel/sched_fair.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
Index: linux-2.6/kernel/sched_fair.c =================================================================== --- linux-2.6.orig/kernel/sched_fair.c +++ linux-2.6/kernel/sched_fair.c @@ -582,19 +582,26 @@ place_entity(struct cfs_rq *cfs_rq, stru } 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 --
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