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  * When converting the wakeup granularity to virtual time, do it such
  21  * that heavier tasks preempting a lighter task have an edge.
  22  */
  23 SCHED_FEAT(ASYM_GRAN, 1)
  24
  25 /*
  26  * Based on load and program behaviour, see if it makes sense to place
  27  * a newly woken task on the same cpu as the task that woke it --
  28  * improve cache locality. Typically used with SYNC wakeups as
  29  * generated by pipes and the like, see also SYNC_WAKEUPS.
  30  */
  31 SCHED_FEAT(AFFINE_WAKEUPS, 1)
  32
  33 /*
  34  * Prefer to schedule the task we woke last (assuming it failed
  35  * wakeup-preemption), since its likely going to consume data we
  36  * touched, increases cache locality.
  37  */
  38 SCHED_FEAT(NEXT_BUDDY, 0)
  39
  40 /*
  41  * Prefer to schedule the task that ran last (when we did
  42  * wake-preempt) as that likely will touch the same data, increases
  43  * cache locality.
  44  */
  45 SCHED_FEAT(LAST_BUDDY, 1)
  46
  47 /*
  48  * Consider buddies to be cache hot, decreases the likelyness of a
  49  * cache buddy being migrated away, increases cache locality.
  50  */
  51 SCHED_FEAT(CACHE_HOT_BUDDY, 1)
  52
  53 /*
  54  * Use arch dependent cpu power functions
  55  */
  56 SCHED_FEAT(ARCH_POWER, 0)
  57
  58 SCHED_FEAT(HRTICK, 0)
  59 SCHED_FEAT(DOUBLE_TICK, 0)
  60 SCHED_FEAT(LB_BIAS, 1)
  61 SCHED_FEAT(LB_SHARES_UPDATE, 1)
  62 SCHED_FEAT(ASYM_EFF_LOAD, 1)
  63
  64 /*
  65  * Spin-wait on mutex acquisition when the mutex owner is running on
  66  * another cpu -- assumes that when the owner is running, it will soon
  67  * release the lock. Decreases scheduling overhead.
  68  */
  69 SCHED_FEAT(OWNER_SPIN, 1)