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 power functions
  41  */
  42 SCHED_FEAT(ARCH_POWER, true)
  43
  44 SCHED_FEAT(HRTICK, false)
  45 SCHED_FEAT(DOUBLE_TICK, false)
  46 SCHED_FEAT(LB_BIAS, true)
  47
  48 /*
  49  * Spin-wait on mutex acquisition when the mutex owner is running on
  50  * another cpu -- assumes that when the owner is running, it will soon
  51  * release the lock. Decreases scheduling overhead.
  52  */
  53 SCHED_FEAT(OWNER_SPIN, true)
  54
  55 /*
  56  * Decrement CPU power based on time not spent running tasks
  57  */
  58 SCHED_FEAT(NONTASK_POWER, true)
  59
  60 /*
  61  * Queue remote wakeups on the target CPU and process them
  62  * using the scheduler IPI. Reduces rq->lock contention/bounces.
  63  */
  64 SCHED_FEAT(TTWU_QUEUE, true)
  65
  66 SCHED_FEAT(FORCE_SD_OVERLAP, false)
  67 SCHED_FEAT(RT_RUNTIME_SHARE, true)
  68 SCHED_FEAT(LB_MIN, false)
  69
  70 /*
  71  * Apply the automatic NUMA scheduling policy. Enabled automatically
  72  * at runtime if running on a NUMA machine. Can be controlled via
  73  * numa_balancing=. Allow PTE scanning to be forced on UMA machines
  74  * for debugging the core machinery.
  75  */
  76 #ifdef CONFIG_NUMA_BALANCING
  77 SCHED_FEAT(NUMA,        false)
  78 SCHED_FEAT(NUMA_FORCE,  false)
  79 #endif