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