From: Vincent Guittot <vincent.guittot@linaro.org> mainline inclusion from mainline-v6.17-rc1 commit 74eec63661d46a7153d04c2e0249eeb76cc76d44 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8903 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- EEVDF expects the scheduler to allocate a time quantum to the selected entity and then pick a new entity for next quantum. Although this notion of time quantum is not strictly doable in our case, we can ensure a minimum runtime for each task most of the time and pick a new entity after a minimum time has elapsed. Reuse the slice protection of run to parity to ensure such runtime quantum. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20250708165630.1948751-3-vincent.guittot@linaro.or... Conflicts: kernel/sched/fair.c [a trival context conflict] Signed-off-by: Zicheng Qu <quzicheng@huawei.com> --- include/linux/sched.h | 10 +++++++++- kernel/sched/fair.c | 31 ++++++++++++++++++++----------- 2 files changed, 29 insertions(+), 12 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index ccf9b58cf4b8..479c206307d1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -592,7 +592,15 @@ struct sched_entity { u64 sum_exec_runtime; u64 prev_sum_exec_runtime; u64 vruntime; - s64 vlag; + union { + /* + * When !@on_rq this field is vlag. + * When cfs_rq->curr == se (which implies @on_rq) + * this field is vprot. See protect_slice(). + */ + s64 vlag; + u64 vprot; + }; u64 slice; u64 nr_migrations; diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b8ed9382c422..9c2fc59a8c58 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1067,23 +1067,35 @@ struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq) } /* - * HACK, stash a copy of deadline at the point of pick in vlag, - * which isn't used until dequeue. + * Set the vruntime up to which an entity can run before looking + * for another entity to pick. + * In case of run to parity, we protect the entity up to its deadline. + * When run to parity is disabled, we give a minimum quantum to the running + * entity to ensure progress. */ static inline void set_protect_slice(struct sched_entity *se) { - se->vlag = se->deadline; + u64 slice = se->slice; + u64 vprot = se->deadline; + + if (!sched_feat(RUN_TO_PARITY)) + slice = min(slice, normalized_sysctl_sched_base_slice); + + if (slice != se->slice) + vprot = min_vruntime(vprot, se->vruntime + calc_delta_fair(slice, se)); + + se->vprot = vprot; } static inline bool protect_slice(struct sched_entity *se) { - return se->vlag == se->deadline; + return ((s64)(se->vprot - se->vruntime) > 0); } static inline void cancel_protect_slice(struct sched_entity *se) { if (protect_slice(se)) - se->vlag = se->deadline + 1; + se->vprot = se->vruntime; } /* @@ -1138,7 +1150,7 @@ static struct sched_entity *pick_eevdf(struct cfs_rq *cfs_rq, bool wakeup_preemp !entity_eligible(cfs_rq, curr)) curr = NULL; - if (sched_feat(RUN_TO_PARITY) && curr && protect_slice(curr)) + if (curr && protect_slice(curr)) return curr; /* Pick the leftmost entity if it's eligible */ @@ -1372,11 +1384,8 @@ static inline void update_curr_task(struct task_struct *p, s64 delta_exec) cgroup_account_cputime(p, delta_exec); } -static inline bool did_preempt_short(struct cfs_rq *cfs_rq, struct sched_entity *curr) +static inline bool resched_next_slice(struct cfs_rq *cfs_rq, struct sched_entity *curr) { - if (!sched_feat(PREEMPT_SHORT)) - return false; - if (protect_slice(curr)) return false; @@ -1447,7 +1456,7 @@ static void update_curr(struct cfs_rq *cfs_rq) if (cfs_rq->nr_running == 1) return; - if (resched || did_preempt_short(cfs_rq, curr)) { + if (resched || resched_next_slice(cfs_rq, curr)) { resched_curr(rq); clear_buddies(cfs_rq, curr); } -- 2.34.1