1 /* 2 * Only give sleepers 50% of their service deficit. This allows 3 * them to run sooner, but does not allow tons of sleepers to 4 * rip the spread apart. 5 */ 6 SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true) 7 8 /* 9 * Place new tasks ahead so that they do not starve already running 10 * tasks 11 */ 12 SCHED_FEAT(START_DEBIT, true) 13 14 /* 15 * Prefer to schedule the task we woke last (assuming it failed 16 * wakeup-preemption), since its likely going to consume data we 17 * touched, increases cache locality. 18 */ 19 SCHED_FEAT(NEXT_BUDDY, false) 20 21 /* 22 * Prefer to schedule the task that ran last (when we did 23 * wake-preempt) as that likely will touch the same data, increases 24 * cache locality. 25 */ 26 SCHED_FEAT(LAST_BUDDY, true) 27 28 /* 29 * Consider buddies to be cache hot, decreases the likelyness of a 30 * cache buddy being migrated away, increases cache locality. 31 */ 32 SCHED_FEAT(CACHE_HOT_BUDDY, true) 33 34 /* 35 * Allow wakeup-time preemption of the current task: 36 */ 37 SCHED_FEAT(WAKEUP_PREEMPTION, true) 38 39 SCHED_FEAT(HRTICK, false) 40 SCHED_FEAT(DOUBLE_TICK, false) 41 SCHED_FEAT(LB_BIAS, true) 42 43 /* 44 * Decrement CPU capacity based on time not spent running tasks 45 */ 46 SCHED_FEAT(NONTASK_CAPACITY, true) 47 48 /* 49 * Queue remote wakeups on the target CPU and process them 50 * using the scheduler IPI. Reduces rq->lock contention/bounces. 51 */ 52 SCHED_FEAT(TTWU_QUEUE, true) 53 54 /* 55 * When doing wakeups, attempt to limit superfluous scans of the LLC domain. 56 */ 57 SCHED_FEAT(SIS_AVG_CPU, false) 58 59 /* 60 * Issue a WARN when we do multiple update_rq_clock() calls 61 * in a single rq->lock section. Default disabled because the 62 * annotations are not complete. 63 */ 64 SCHED_FEAT(WARN_DOUBLE_CLOCK, false) 65 66 #ifdef HAVE_RT_PUSH_IPI 67 /* 68 * In order to avoid a thundering herd attack of CPUs that are 69 * lowering their priorities at the same time, and there being 70 * a single CPU that has an RT task that can migrate and is waiting 71 * to run, where the other CPUs will try to take that CPUs 72 * rq lock and possibly create a large contention, sending an 73 * IPI to that CPU and let that CPU push the RT task to where 74 * it should go may be a better scenario. 75 */ 76 SCHED_FEAT(RT_PUSH_IPI, true) 77 #endif 78 79 SCHED_FEAT(FORCE_SD_OVERLAP, false) 80 SCHED_FEAT(RT_RUNTIME_SHARE, true) 81 SCHED_FEAT(LB_MIN, false) 82 SCHED_FEAT(ATTACH_AGE_LOAD, true) 83 84