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sched/eevdf: Update se->vprot in reweight_entity()

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In the EEVDF framework with Run-to-Parity protection, `se->vprot` is an
independent variable defining the virtual protection timestamp.

When `reweight_entity()` is called (e.g., via nice/renice), it performs
the following actions to preserve Lag consistency:
 1. Scales `se->vlag` based on the new weight.
 2. Calls `place_entity()`, which recalculates `se->vruntime` based on
    the new weight and scaled lag.

However, the current implementation fails to update `se->vprot`, leading
to mismatches between the task's actual runtime and its expected duration.

Fixes: 63304558ba ("sched/eevdf: Curb wakeup-preemption")
Suggested-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Wang Tao <wangtao554@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Shubhang Kaushik <shubhang@os.amperecomputing.com>
Link: https://patch.msgid.link/20260120123113.3518950-1-wangtao554@huawei.com
This commit is contained in:
Wang Tao 2026-01-20 12:31:13 +00:00 • committed by Peter Zijlstra
parent bcd74b2ffd
commit ff38424030
1 changed files with 12 additions and 0 deletions
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12
kernel/sched/fair.c
View file

@ -3815,6 +3815,8 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
unsigned long weight)
{
bool curr = cfs_rq->curr == se;
bool rel_vprot = false;
u64 vprot;
if (se->on_rq) {
/* commit outstanding execution time */
@ -3822,6 +3824,11 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
update_entity_lag(cfs_rq, se);
se->deadline -= se->vruntime;
se->rel_deadline = 1;
if (curr && protect_slice(se)) {
vprot = se->vprot - se->vruntime;
rel_vprot = true;
}
cfs_rq->nr_queued--;
if (!curr)
__dequeue_entity(cfs_rq, se);
@ -3837,6 +3844,9 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
if (se->rel_deadline)
se->deadline = div_s64(se->deadline * se->load.weight, weight);
if (rel_vprot)
vprot = div_s64(vprot * se->load.weight, weight);
update_load_set(&se->load, weight);
do {
@ -3848,6 +3858,8 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
enqueue_load_avg(cfs_rq, se);
if (se->on_rq) {
place_entity(cfs_rq, se, 0);
if (rel_vprot)
se->vprot = se->vruntime + vprot;
update_load_add(&cfs_rq->load, se->load.weight);
if (!curr)
__enqueue_entity(cfs_rq, se);