LXR linux/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 */
   6SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true)
   7
   8/*
   9 * Place new tasks ahead so that they do not starve already running
  10 * tasks
  11 */
  12SCHED_FEAT(START_DEBIT, true)
  13
  14/*
  15 * Prefer to schedule the task we woke last (assuming it failed
  16 * wakeup-preemption), since its likely going to consume data we
  17 * touched, increases cache locality.
  18 */
  19SCHED_FEAT(NEXT_BUDDY, false)
  20
  21/*
  22 * Prefer to schedule the task that ran last (when we did
  23 * wake-preempt) as that likely will touch the same data, increases
  24 * cache locality.
  25 */
  26SCHED_FEAT(LAST_BUDDY, true)
  27
  28/*
  29 * Consider buddies to be cache hot, decreases the likelyness of a
  30 * cache buddy being migrated away, increases cache locality.
  31 */
  32SCHED_FEAT(CACHE_HOT_BUDDY, true)
  33
  34/*
  35 * Allow wakeup-time preemption of the current task:
  36 */
  37SCHED_FEAT(WAKEUP_PREEMPTION, true)
  38
  39SCHED_FEAT(HRTICK, false)
  40SCHED_FEAT(DOUBLE_TICK, false)
  41SCHED_FEAT(LB_BIAS, true)
  42
  43/*
  44 * Decrement CPU capacity based on time not spent running tasks
  45 */
  46SCHED_FEAT(NONTASK_CAPACITY, true)
  47
  48/*
  49 * Queue remote wakeups on the target CPU and process them
  50 * using the scheduler IPI. Reduces rq->lock contention/bounces.
  51 */
  52SCHED_FEAT(TTWU_QUEUE, true)
  53
  54#ifdef HAVE_RT_PUSH_IPI
  55/*
  56 * In order to avoid a thundering herd attack of CPUs that are
  57 * lowering their priorities at the same time, and there being
  58 * a single CPU that has an RT task that can migrate and is waiting
  59 * to run, where the other CPUs will try to take that CPUs
  60 * rq lock and possibly create a large contention, sending an
  61 * IPI to that CPU and let that CPU push the RT task to where
  62 * it should go may be a better scenario.
  63 */
  64SCHED_FEAT(RT_PUSH_IPI, true)
  65#endif
  66
  67SCHED_FEAT(FORCE_SD_OVERLAP, false)
  68SCHED_FEAT(RT_RUNTIME_SHARE, true)
  69SCHED_FEAT(LB_MIN, false)
  70SCHED_FEAT(ATTACH_AGE_LOAD, true)
  71
  72