diff options
| -rw-r--r-- | kernel/sched/fair.c | 71 |
1 files changed, 69 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2547a97921ac..c5759107b8be 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -777,6 +777,67 @@ u64 avg_vruntime(struct cfs_rq *cfs_rq) return cfs_rq->zero_vruntime; } +/* + * \Sum (v_i - v0)*w_i + * V = ------------------- + v0 + * \Sum w_i + * + * Let W = \Sum w_i, and move v_j such that 'v_j == V', thus: + * + * V = 1/W * {(v_j - v0)*w_j + \Sum_i!=j (v_i - v0)*w_i} + v0 + * + * v_j = 1/W * {(v_j - v0)*w_j + \Sum_i!=j (v_i - v0)*w_i} + v0 + * + * v_j = 1/W * (v_j - v0)*w_j + 1/W * \Sum_i!=j (v_i - v0)*w_i + v0 + * + * v_j - 1/W * (v_j - v0)*w_j = 1/W * \Sum_i!=j (v_i - v0)*w_i + v0 + * + * v_j*W - (v_j - v0)*w_j = \Sum_i!=j (v_i - v0)*w_i + v0*W + * + * v_j*(W - w_j) + v0*w_j = \Sum_i!=j (v_i - v0)*w_i + v0*W + * + * v_j*(W - w_j) = \Sum_i!=j (v_i - v0)*w_i + v0*(W - w_j) + * + * \Sum_i!=j (v_i - v0)*w_i + * v_j = ------------------------ + v0 + * W - w_j + * + * When v_j happens to be curr, then '\Sum_i!=j (v_i - v0)*w_i' + * is cfs_rq->sum_w_runtime, and 'W - w_j' is cfs_rq->sum_weight, since curr + * is not included in the sum. + */ +static u64 ineligible_vruntime(struct cfs_rq *cfs_rq) +{ + struct sched_entity *curr = cfs_rq->curr; + long weight = cfs_rq->sum_weight; + s64 delta = 0; + + if (curr && !curr->on_rq) + curr = NULL; + + /* + * This is called from set_next_task_fair(.first=true) / + * set_protect_slice() so curr had better be set and on_rq. + */ + WARN_ON_ONCE(!curr); + + if (weight) { + s64 runtime = cfs_rq->sum_w_vruntime; + + /* + * Do not add @curr to obtain the effective '- w_j' terms. + */ + + /* sign flips effective floor / ceiling */ + if (runtime < 0) + runtime -= (weight - 1); + + delta = div64_long(runtime, weight); + } + + return cfs_rq->zero_vruntime + delta + 1; +} + static inline u64 cfs_rq_max_slice(struct cfs_rq *cfs_rq); /* @@ -1058,8 +1119,14 @@ static inline void set_protect_slice(struct cfs_rq *cfs_rq, struct sched_entity slice = cfs_rq_min_slice(cfs_rq); slice = min(slice, se->slice); - if (slice != se->slice) - vprot = min_vruntime(vprot, se->vruntime + calc_delta_fair(slice, se)); + + /* If there are shorter slices than se's one */ + if (slice != se->slice) { + if (sched_feat(PREEMPT_SHORT)) + vprot = min_vruntime(vprot, ineligible_vruntime(cfs_rq)); + else + vprot = min_vruntime(vprot, se->vruntime + calc_delta_fair(slice, se)); + } se->vprot = vprot; } |