Messages in this thread Patch in this message | | | From | Byungchul Park <> | Subject | [PATCH] sched/fair: Fix update_min_vruntime() to get proper min_vruntime | Date | Tue, 6 Sep 2016 14:05:17 +0900 |
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I am sorry for making you confused. The patch I posted one year ago, Commit 97a7142 'sched/fair: Make update_min_vruntime() more readable', has a bug, which you picked up.
Please add this patch to fix it, or combine these two patches into one, or revert commit 97a7142. Whatever you want. Sorry.
Thank you, Byungchul
-----8<----- From 295895be8befbab040d6054bb8186c03daabcedd Mon Sep 17 00:00:00 2001 From: Byungchul Park <byungchul.park@lge.com> Date: Tue, 6 Sep 2016 12:22:26 +0900 Subject: [PATCH] sched/fair: Fix update_min_vruntime() to get proper min_vruntime
Commit 97a7142 'sched/fair: Make update_min_vruntime() more readable' introduces a bug that cfs_rq gets a wrong min_vruntime if !cfs_rq->rb_leftmost && cfs_rq->curr. This fixes it and makes it more readable and simple.
Signed-off-by: Byungchul Park <byungchul.park@lge.com> --- kernel/sched/fair.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index a6820b3..0a5f666b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -462,21 +462,20 @@ static inline int entity_before(struct sched_entity *a, static void update_min_vruntime(struct cfs_rq *cfs_rq) { - u64 vruntime = cfs_rq->min_vruntime; - - if (cfs_rq->rb_leftmost) { - struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost, - struct sched_entity, - run_node); + u64 vruntime = U64_MAX; - vruntime = se->vruntime; - } + if (cfs_rq->rb_leftmost) + vruntime = rb_entry(cfs_rq->rb_leftmost, + struct sched_entity, + run_node)->vruntime; if (cfs_rq->curr) vruntime = min_vruntime(vruntime, cfs_rq->curr->vruntime); /* ensure we never gain time by being placed backwards. */ - cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); + if (vruntime != U64_MAX) + cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); + #ifndef CONFIG_64BIT smp_wmb(); cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; -- 1.9.1
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