kernel/sched/features.h

   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 SCHED_FEAT(FORCE_SD_OVERLAP, false)
  60 SCHED_FEAT(RT_RUNTIME_SHARE, true)
  61 SCHED_FEAT(LB_MIN, false)
  62
  63 /*
  64  * Apply the automatic NUMA scheduling policy. Enabled automatically
  65  * at runtime if running on a NUMA machine. Can be controlled via
  66  * numa_balancing=
  67  */
  68 #ifdef CONFIG_NUMA_BALANCING
  69 SCHED_FEAT(NUMA,        false)
  70
  71 /*
  72  * NUMA_FAVOUR_HIGHER will favor moving tasks towards nodes where a
  73  * higher number of hinting faults are recorded during active load
  74  * balancing.
  75  */
  76 SCHED_FEAT(NUMA_FAVOUR_HIGHER, true)
  77
  78 /*
  79  * NUMA_RESIST_LOWER will resist moving tasks towards nodes where a
  80  * lower number of hinting faults have been recorded. As this has
  81  * the potential to prevent a task ever migrating to a new node
  82  * due to CPU overload it is disabled by default.
  83  */
  84 SCHED_FEAT(NUMA_RESIST_LOWER, false)
  85 #endif