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  * Always wakeup-preempt SYNC wakeups, see SYNC_WAKEUPS.
  27  */
  28 SCHED_FEAT(WAKEUP_SYNC, 0)
  29
  30 /*
  31  * Use the SYNC wakeup hint, pipes and the likes use this to indicate
  32  * the remote end is likely to consume the data we just wrote, and
  33  * therefore has cache benefit from being placed on the same cpu, see
  34  * also AFFINE_WAKEUPS.
  35  */
  36 SCHED_FEAT(SYNC_WAKEUPS, 1)
  37
  38 /*
  39  * Based on load and program behaviour, see if it makes sense to place
  40  * a newly woken task on the same cpu as the task that woke it --
  41  * improve cache locality. Typically used with SYNC wakeups as
  42  * generated by pipes and the like, see also SYNC_WAKEUPS.
  43  */
  44 SCHED_FEAT(AFFINE_WAKEUPS, 1)
  45
  46 /*
  47  * Prefer to schedule the task we woke last (assuming it failed
  48  * wakeup-preemption), since its likely going to consume data we
  49  * touched, increases cache locality.
  50  */
  51 SCHED_FEAT(NEXT_BUDDY, 0)
  52
  53 /*
  54  * Prefer to schedule the task that ran last (when we did
  55  * wake-preempt) as that likely will touch the same data, increases
  56  * cache locality.
  57  */
  58 SCHED_FEAT(LAST_BUDDY, 1)
  59
  60 /*
  61  * Consider buddies to be cache hot, decreases the likelyness of a
  62  * cache buddy being migrated away, increases cache locality.
  63  */
  64 SCHED_FEAT(CACHE_HOT_BUDDY, 1)
  65
  66 /*
  67  * Use arch dependent cpu power functions
  68  */
  69 SCHED_FEAT(ARCH_POWER, 0)
  70
  71 SCHED_FEAT(HRTICK, 0)
  72 SCHED_FEAT(DOUBLE_TICK, 0)
  73 SCHED_FEAT(LB_BIAS, 1)
  74 SCHED_FEAT(LB_SHARES_UPDATE, 1)
  75 SCHED_FEAT(ASYM_EFF_LOAD, 1)
  76
  77 /*
  78  * Spin-wait on mutex acquisition when the mutex owner is running on
  79  * another cpu -- assumes that when the owner is running, it will soon
  80  * release the lock. Decreases scheduling overhead.
  81  */
  82 SCHED_FEAT(OWNER_SPIN, 1)