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 /* 40 * Use arch dependent cpu capacity functions 41 */ 42 SCHED_FEAT(ARCH_CAPACITY, true) 43 44 SCHED_FEAT(HRTICK, false) 45 SCHED_FEAT(DOUBLE_TICK, false) 46 SCHED_FEAT(LB_BIAS, true) 47 48 /* 49 * Decrement CPU capacity based on time not spent running tasks 50 */ 51 SCHED_FEAT(NONTASK_CAPACITY, true) 52 53 /* 54 * Queue remote wakeups on the target CPU and process them 55 * using the scheduler IPI. Reduces rq->lock contention/bounces. 56 */ 57 SCHED_FEAT(TTWU_QUEUE, true) 58 59 #ifdef HAVE_RT_PUSH_IPI 60 /* 61 * In order to avoid a thundering herd attack of CPUs that are 62 * lowering their priorities at the same time, and there being 63 * a single CPU that has an RT task that can migrate and is waiting 64 * to run, where the other CPUs will try to take that CPUs 65 * rq lock and possibly create a large contention, sending an 66 * IPI to that CPU and let that CPU push the RT task to where 67 * it should go may be a better scenario. 68 */ 69 SCHED_FEAT(RT_PUSH_IPI, true) 70 #endif 71 72 SCHED_FEAT(FORCE_SD_OVERLAP, false) 73 SCHED_FEAT(RT_RUNTIME_SHARE, true) 74 SCHED_FEAT(LB_MIN, false) 75 76 /* 77 * Apply the automatic NUMA scheduling policy. Enabled automatically 78 * at runtime if running on a NUMA machine. Can be controlled via 79 * numa_balancing= 80 */ 81 #ifdef CONFIG_NUMA_BALANCING 82 SCHED_FEAT(NUMA, false) 83 84 /* 85 * NUMA_FAVOUR_HIGHER will favor moving tasks towards nodes where a 86 * higher number of hinting faults are recorded during active load 87 * balancing. 88 */ 89 SCHED_FEAT(NUMA_FAVOUR_HIGHER, true) 90 91 /* 92 * NUMA_RESIST_LOWER will resist moving tasks towards nodes where a 93 * lower number of hinting faults have been recorded. As this has 94 * the potential to prevent a task ever migrating to a new node 95 * due to CPU overload it is disabled by default. 96 */ 97 SCHED_FEAT(NUMA_RESIST_LOWER, false) 98 #endif 99