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, 1)
   7
   8 /*
   9  * Place new tasks ahead so that they do not starve already running
  10  * tasks
  11  */
  12 SCHED_FEAT(START_DEBIT, 1)
  13
  14 /*
  15  * Should wakeups try to preempt running tasks.
  16  */
  17 SCHED_FEAT(WAKEUP_PREEMPT, 1)
  18
  19 /*
  20  * Based on load and program behaviour, see if it makes sense to place
  21  * a newly woken task on the same cpu as the task that woke it --
  22  * improve cache locality. Typically used with SYNC wakeups as
  23  * generated by pipes and the like, see also SYNC_WAKEUPS.
  24  */
  25 SCHED_FEAT(AFFINE_WAKEUPS, 1)
  26
  27 /*
  28  * Prefer to schedule the task we woke last (assuming it failed
  29  * wakeup-preemption), since its likely going to consume data we
  30  * touched, increases cache locality.
  31  */
  32 SCHED_FEAT(NEXT_BUDDY, 0)
  33
  34 /*
  35  * Prefer to schedule the task that ran last (when we did
  36  * wake-preempt) as that likely will touch the same data, increases
  37  * cache locality.
  38  */
  39 SCHED_FEAT(LAST_BUDDY, 1)
  40
  41 /*
  42  * Consider buddies to be cache hot, decreases the likelyness of a
  43  * cache buddy being migrated away, increases cache locality.
  44  */
  45 SCHED_FEAT(CACHE_HOT_BUDDY, 1)
  46
  47 /*
  48  * Use arch dependent cpu power functions
  49  */
  50 SCHED_FEAT(ARCH_POWER, 0)
  51
  52 SCHED_FEAT(HRTICK, 0)
  53 SCHED_FEAT(DOUBLE_TICK, 0)
  54 SCHED_FEAT(LB_BIAS, 1)
  55
  56 /*
  57  * Spin-wait on mutex acquisition when the mutex owner is running on
  58  * another cpu -- assumes that when the owner is running, it will soon
  59  * release the lock. Decreases scheduling overhead.
  60  */
  61 SCHED_FEAT(OWNER_SPIN, 1)
  62
  63 /*
  64  * Decrement CPU power based on irq activity
  65  */
  66 SCHED_FEAT(NONIRQ_POWER, 1)
  67
  68 /*
  69  * Queue remote wakeups on the target CPU and process them
  70  * using the scheduler IPI. Reduces rq->lock contention/bounces.
  71  */
  72 SCHED_FEAT(TTWU_QUEUE, 1)