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  * Based on load and program behaviour, see if it makes sense to place
  16  * a newly woken task on the same cpu as the task that woke it --
  17  * improve cache locality. Typically used with SYNC wakeups as
  18  * generated by pipes and the like, see also SYNC_WAKEUPS.
  19  */
  20 SCHED_FEAT(AFFINE_WAKEUPS, true)
  21
  22 /*
  23  * Prefer to schedule the task we woke last (assuming it failed
  24  * wakeup-preemption), since its likely going to consume data we
  25  * touched, increases cache locality.
  26  */
  27 SCHED_FEAT(NEXT_BUDDY, false)
  28
  29 /*
  30  * Prefer to schedule the task that ran last (when we did
  31  * wake-preempt) as that likely will touch the same data, increases
  32  * cache locality.
  33  */
  34 SCHED_FEAT(LAST_BUDDY, true)
  35
  36 /*
  37  * Consider buddies to be cache hot, decreases the likelyness of a
  38  * cache buddy being migrated away, increases cache locality.
  39  */
  40 SCHED_FEAT(CACHE_HOT_BUDDY, true)
  41
  42 /*
  43  * Use arch dependent cpu power functions
  44  */
  45 SCHED_FEAT(ARCH_POWER, false)
  46
  47 SCHED_FEAT(HRTICK, false)
  48 SCHED_FEAT(DOUBLE_TICK, false)
  49 SCHED_FEAT(LB_BIAS, true)
  50
  51 /*
  52  * Spin-wait on mutex acquisition when the mutex owner is running on
  53  * another cpu -- assumes that when the owner is running, it will soon
  54  * release the lock. Decreases scheduling overhead.
  55  */
  56 SCHED_FEAT(OWNER_SPIN, true)
  57
  58 /*
  59  * Decrement CPU power based on time not spent running tasks
  60  */
  61 SCHED_FEAT(NONTASK_POWER, true)
  62
  63 /*
  64  * Queue remote wakeups on the target CPU and process them
  65  * using the scheduler IPI. Reduces rq->lock contention/bounces.
  66  */
  67 SCHED_FEAT(TTWU_QUEUE, true)
  68
  69 SCHED_FEAT(FORCE_SD_OVERLAP, false)
  70 SCHED_FEAT(RT_RUNTIME_SHARE, true)