| Peter Zijlstra | e26af0e | 2009-09-11 12:31:23 +0200 | [diff] [blame] | 1 | /* |
| Ingo Molnar | 51e0304 | 2009-09-16 08:54:45 +0200 | [diff] [blame] | 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 | */ |
| Peter Zijlstra | f8b6d1c | 2011-07-06 14:20:14 +0200 | [diff] [blame] | 6 | SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true) |
| Peter Zijlstra | e26af0e | 2009-09-11 12:31:23 +0200 | [diff] [blame] | 7 | |
| 8 | /* |
| Peter Zijlstra | e26af0e | 2009-09-11 12:31:23 +0200 | [diff] [blame] | 9 | * Place new tasks ahead so that they do not starve already running |
| 10 | * tasks |
| 11 | */ |
| Peter Zijlstra | f8b6d1c | 2011-07-06 14:20:14 +0200 | [diff] [blame] | 12 | SCHED_FEAT(START_DEBIT, true) |
| Peter Zijlstra | e26af0e | 2009-09-11 12:31:23 +0200 | [diff] [blame] | 13 | |
| 14 | /* |
| Peter Zijlstra | e26af0e | 2009-09-11 12:31:23 +0200 | [diff] [blame] | 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 | */ |
| Peter Zijlstra | f8b6d1c | 2011-07-06 14:20:14 +0200 | [diff] [blame] | 19 | SCHED_FEAT(NEXT_BUDDY, false) |
| Peter Zijlstra | e26af0e | 2009-09-11 12:31:23 +0200 | [diff] [blame] | 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 | */ |
| Peter Zijlstra | f8b6d1c | 2011-07-06 14:20:14 +0200 | [diff] [blame] | 26 | SCHED_FEAT(LAST_BUDDY, true) |
| Peter Zijlstra | e26af0e | 2009-09-11 12:31:23 +0200 | [diff] [blame] | 27 | |
| 28 | /* |
| 29 | * Consider buddies to be cache hot, decreases the likelyness of a |
| 30 | * cache buddy being migrated away, increases cache locality. |
| 31 | */ |
| Peter Zijlstra | f8b6d1c | 2011-07-06 14:20:14 +0200 | [diff] [blame] | 32 | SCHED_FEAT(CACHE_HOT_BUDDY, true) |
| Peter Zijlstra | e26af0e | 2009-09-11 12:31:23 +0200 | [diff] [blame] | 33 | |
| Peter Zijlstra | 8e6598a | 2009-09-03 13:20:03 +0200 | [diff] [blame] | 34 | /* |
| Ingo Molnar | 8ed92e5 | 2012-10-14 14:28:50 +0200 | [diff] [blame] | 35 | * Allow wakeup-time preemption of the current task: |
| 36 | */ |
| 37 | SCHED_FEAT(WAKEUP_PREEMPTION, true) |
| 38 | |
| Peter Zijlstra | f8b6d1c | 2011-07-06 14:20:14 +0200 | [diff] [blame] | 39 | SCHED_FEAT(HRTICK, false) |
| 40 | SCHED_FEAT(DOUBLE_TICK, false) |
| 41 | SCHED_FEAT(LB_BIAS, true) |
| Peter Zijlstra | e26af0e | 2009-09-11 12:31:23 +0200 | [diff] [blame] | 42 | |
| 43 | /* |
| Nicolas Pitre | 5d4dfdd | 2014-05-27 13:50:41 -0400 | [diff] [blame] | 44 | * Decrement CPU capacity based on time not spent running tasks |
| Venkatesh Pallipadi | aa48380 | 2010-10-04 17:03:22 -0700 | [diff] [blame] | 45 | */ |
| Nicolas Pitre | 5d4dfdd | 2014-05-27 13:50:41 -0400 | [diff] [blame] | 46 | SCHED_FEAT(NONTASK_CAPACITY, true) |
| Peter Zijlstra | 317f394 | 2011-04-05 17:23:58 +0200 | [diff] [blame] | 47 | |
| 48 | /* |
| 49 | * Queue remote wakeups on the target CPU and process them |
| 50 | * using the scheduler IPI. Reduces rq->lock contention/bounces. |
| 51 | */ |
| Peter Zijlstra | f8b6d1c | 2011-07-06 14:20:14 +0200 | [diff] [blame] | 52 | SCHED_FEAT(TTWU_QUEUE, true) |
| Peter Zijlstra | e3589f6 | 2011-07-15 10:35:52 +0200 | [diff] [blame] | 53 | |
| Peter Zijlstra | 4c77b18 | 2017-03-01 11:24:35 +0100 | [diff] [blame] | 54 | /* |
| 55 | * When doing wakeups, attempt to limit superfluous scans of the LLC domain. |
| 56 | */ |
| 57 | SCHED_FEAT(SIS_AVG_CPU, false) |
| Peter Zijlstra | 1ad3aaf | 2017-05-17 12:53:50 +0200 | [diff] [blame] | 58 | SCHED_FEAT(SIS_PROP, true) |
| Peter Zijlstra | 4c77b18 | 2017-03-01 11:24:35 +0100 | [diff] [blame] | 59 | |
| Peter Zijlstra | 26ae58d | 2016-10-03 16:53:49 +0200 | [diff] [blame] | 60 | /* |
| 61 | * Issue a WARN when we do multiple update_rq_clock() calls |
| 62 | * in a single rq->lock section. Default disabled because the |
| 63 | * annotations are not complete. |
| 64 | */ |
| 65 | SCHED_FEAT(WARN_DOUBLE_CLOCK, false) |
| 66 | |
| Steven Rostedt | b6366f0 | 2015-03-18 14:49:46 -0400 | [diff] [blame] | 67 | #ifdef HAVE_RT_PUSH_IPI |
| 68 | /* |
| 69 | * In order to avoid a thundering herd attack of CPUs that are |
| 70 | * lowering their priorities at the same time, and there being |
| 71 | * a single CPU that has an RT task that can migrate and is waiting |
| 72 | * to run, where the other CPUs will try to take that CPUs |
| 73 | * rq lock and possibly create a large contention, sending an |
| 74 | * IPI to that CPU and let that CPU push the RT task to where |
| 75 | * it should go may be a better scenario. |
| 76 | */ |
| 77 | SCHED_FEAT(RT_PUSH_IPI, true) |
| 78 | #endif |
| 79 | |
| Peter Zijlstra | f8b6d1c | 2011-07-06 14:20:14 +0200 | [diff] [blame] | 80 | SCHED_FEAT(RT_RUNTIME_SHARE, true) |
| Peter Zijlstra | eb95308 | 2012-04-17 13:38:40 +0200 | [diff] [blame] | 81 | SCHED_FEAT(LB_MIN, false) |
| Peter Zijlstra | a928051 | 2015-09-11 16:10:59 +0200 | [diff] [blame] | 82 | SCHED_FEAT(ATTACH_AGE_LOAD, true) |
| 83 | |