1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Only give sleepers 50% of their service deficit. This allows 4 * them to run sooner, but does not allow tons of sleepers to 5 * rip the spread apart. 6 */ 7 SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true) 8 9 /* 10 * Place new tasks ahead so that they do not starve already running 11 * tasks 12 */ 13 SCHED_FEAT(START_DEBIT, true) 14 15 /* 16 * Prefer to schedule the task we woke last (assuming it failed 17 * wakeup-preemption), since its likely going to consume data we 18 * touched, increases cache locality. 19 */ 20 SCHED_FEAT(NEXT_BUDDY, false) 21 22 /* 23 * Prefer to schedule the task that ran last (when we did 24 * wake-preempt) as that likely will touch the same data, increases 25 * cache locality. 26 */ 27 SCHED_FEAT(LAST_BUDDY, true) 28 29 /* 30 * Consider buddies to be cache hot, decreases the likelyness of a 31 * cache buddy being migrated away, increases cache locality. 32 */ 33 SCHED_FEAT(CACHE_HOT_BUDDY, true) 34 35 /* 36 * Allow wakeup-time preemption of the current task: 37 */ 38 SCHED_FEAT(WAKEUP_PREEMPTION, true) 39 40 SCHED_FEAT(HRTICK, false) 41 SCHED_FEAT(DOUBLE_TICK, false) 42 SCHED_FEAT(LB_BIAS, true) 43 44 /* 45 * Decrement CPU capacity based on time not spent running tasks 46 */ 47 SCHED_FEAT(NONTASK_CAPACITY, true) 48 49 /* 50 * Queue remote wakeups on the target CPU and process them 51 * using the scheduler IPI. Reduces rq->lock contention/bounces. 52 */ 53 SCHED_FEAT(TTWU_QUEUE, true) 54 55 /* 56 * When doing wakeups, attempt to limit superfluous scans of the LLC domain. 57 */ 58 SCHED_FEAT(SIS_AVG_CPU, false) 59 SCHED_FEAT(SIS_PROP, true) 60 61 /* 62 * Issue a WARN when we do multiple update_rq_clock() calls 63 * in a single rq->lock section. Default disabled because the 64 * annotations are not complete. 65 */ 66 SCHED_FEAT(WARN_DOUBLE_CLOCK, false) 67 68 #ifdef HAVE_RT_PUSH_IPI 69 /* 70 * In order to avoid a thundering herd attack of CPUs that are 71 * lowering their priorities at the same time, and there being 72 * a single CPU that has an RT task that can migrate and is waiting 73 * to run, where the other CPUs will try to take that CPUs 74 * rq lock and possibly create a large contention, sending an 75 * IPI to that CPU and let that CPU push the RT task to where 76 * it should go may be a better scenario. 77 */ 78 SCHED_FEAT(RT_PUSH_IPI, true) 79 #endif 80 81 SCHED_FEAT(RT_RUNTIME_SHARE, true) 82 SCHED_FEAT(LB_MIN, false) 83 SCHED_FEAT(ATTACH_AGE_LOAD, true) 84 85 SCHED_FEAT(WA_IDLE, true) 86 SCHED_FEAT(WA_WEIGHT, true) 87 SCHED_FEAT(WA_BIAS, true) 88 89 /* 90 * UtilEstimation. Use estimated CPU utilization. 91 */ 92 SCHED_FEAT(UTIL_EST, true) 93 94 /* 95 * Energy aware scheduling. Use platform energy model to guide scheduling 96 * decisions optimizing for energy efficiency. 97 */ 98 #ifdef CONFIG_DEFAULT_USE_ENERGY_AWARE 99 SCHED_FEAT(ENERGY_AWARE, true) 100 #else 101 SCHED_FEAT(ENERGY_AWARE, false) 102 #endif 103 104 /* 105 * Energy aware scheduling algorithm choices: 106 * EAS_PREFER_IDLE 107 * Direct tasks in a schedtune.prefer_idle=1 group through 108 * the EAS path for wakeup task placement. Otherwise, put 109 * those tasks through the mainline slow path. 110 * FIND_BEST_TARGET 111 * Limit the number of placement options for which we calculate 112 * energy by using heuristics to select 'best idle' and 113 * 'best active' cpu options. 114 * FBT_STRICT_ORDER 115 * ON: If the target CPU saves any energy, use that. 116 * OFF: Use whichever of target or backup saves most. 117 */ 118 SCHED_FEAT(EAS_PREFER_IDLE, true) 119 SCHED_FEAT(FIND_BEST_TARGET, true) 120 SCHED_FEAT(FBT_STRICT_ORDER, true) 121 122 /* 123 * Apply schedtune boost hold to tasks of all sched classes. 124 * If enabled, schedtune will hold the boost applied to a CPU 125 * for 50ms regardless of task activation - if the task is 126 * still running 50ms later, the boost hold expires and schedtune 127 * boost will expire immediately the task stops. 128 * If disabled, this behaviour will only apply to tasks of the 129 * RT class. 130 */ 131 SCHED_FEAT(SCHEDTUNE_BOOST_HOLD_ALL, false) 132