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linux-libre
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kernel
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sched
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features.h

features.h 2.0 KB
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  1. /*
    2. 

  2.  * Only give sleepers 50% of their service deficit. This allows
    3. 

  3.  * them to run sooner, but does not allow tons of sleepers to
    4. 

  4.  * rip the spread apart.
    5. 

  5.  */
    6. 

  6. SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true)
    7. 

  7. 

  8. /*
    9. 

  9.  * Place new tasks ahead so that they do not starve already running
    10. 

  10.  * tasks
    11. 

  11.  */
    12. 

  12. SCHED_FEAT(START_DEBIT, true)
    13. 

  13. 

  14. /*
    15. 

  15.  * Prefer to schedule the task we woke last (assuming it failed
    16. 

  16.  * wakeup-preemption), since its likely going to consume data we
    17. 

  17.  * touched, increases cache locality.
    18. 

  18.  */
    19. 

  19. SCHED_FEAT(NEXT_BUDDY, false)
    20. 

  20. 

  21. /*
    22. 

  22.  * Prefer to schedule the task that ran last (when we did
    23. 

  23.  * wake-preempt) as that likely will touch the same data, increases
    24. 

  24.  * cache locality.
    25. 

  25.  */
    26. 

  26. SCHED_FEAT(LAST_BUDDY, true)
    27. 

  27. 

  28. /*
    29. 

  29.  * Consider buddies to be cache hot, decreases the likelyness of a
    30. 

  30.  * cache buddy being migrated away, increases cache locality.
    31. 

  31.  */
    32. 

  32. SCHED_FEAT(CACHE_HOT_BUDDY, true)
    33. 

  33. 

  34. /*
    35. 

  35.  * Allow wakeup-time preemption of the current task:
    36. 

  36.  */
    37. 

  37. SCHED_FEAT(WAKEUP_PREEMPTION, true)
    38. 

  38. 

  39. SCHED_FEAT(HRTICK, false)
    40. 

  40. SCHED_FEAT(DOUBLE_TICK, false)
    41. 

  41. SCHED_FEAT(LB_BIAS, true)
    42. 

  42. 

  43. /*
    44. 

  44.  * Decrement CPU capacity based on time not spent running tasks
    45. 

  45.  */
    46. 

  46. SCHED_FEAT(NONTASK_CAPACITY, true)
    47. 

  47. 

  48. /*
    49. 

  49.  * Queue remote wakeups on the target CPU and process them
    50. 

  50.  * using the scheduler IPI. Reduces rq->lock contention/bounces.
    51. 

  51.  */
    52. 

  52. SCHED_FEAT(TTWU_QUEUE, true)
    53. 

  53. 

  54. /*
    55. 

  55.  * When doing wakeups, attempt to limit superfluous scans of the LLC domain.
    56. 

  56.  */
    57. 

  57. SCHED_FEAT(SIS_AVG_CPU, false)
    58. 

  58. 

  59. #ifdef HAVE_RT_PUSH_IPI
    60. 

  60. /*
    61. 

  61.  * In order to avoid a thundering herd attack of CPUs that are
    62. 

  62.  * lowering their priorities at the same time, and there being
    63. 

  63.  * a single CPU that has an RT task that can migrate and is waiting
    64. 

  64.  * to run, where the other CPUs will try to take that CPUs
    65. 

  65.  * rq lock and possibly create a large contention, sending an
    66. 

  66.  * IPI to that CPU and let that CPU push the RT task to where
    67. 

  67.  * it should go may be a better scenario.
    68. 

  68.  */
    69. 

  69. SCHED_FEAT(RT_PUSH_IPI, true)
    70. 

  70. #endif
    71. 

  71. 

  72. SCHED_FEAT(FORCE_SD_OVERLAP, false)
    73. 

  73. SCHED_FEAT(RT_RUNTIME_SHARE, true)
    74. 

  74. SCHED_FEAT(LB_MIN, false)
    75. 

  75. SCHED_FEAT(ATTACH_AGE_LOAD, true)
    76. 

  76. 

  77.