features.h 1.9 KB

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