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review.shift-gmbh.com / SHIFTPHONES / mainline / linux / b6366f048e0caff28af5335b7af2031266e1b06b / . / kernel / sched / features.h
blob: 91e33cd485f6577050672432c02354393887774e [file] [log] [blame]
Peter Zijlstrae26af0e2009-09-11 12:31:23 +0200[diff] [blame]1/*
Ingo Molnar51e03042009-09-16 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 Zijlstraf8b6d1c2011-07-06 14:20:14 +0200[diff] [blame]6SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true)
Peter Zijlstrae26af0e2009-09-11 12:31:23 +0200[diff] [blame]7
8/*
Peter Zijlstrae26af0e2009-09-11 12:31:23 +0200[diff] [blame]9 * Place new tasks ahead so that they do not starve already running
10 * tasks
11 */
Peter Zijlstraf8b6d1c2011-07-06 14:20:14 +0200[diff] [blame]12SCHED_FEAT(START_DEBIT, true)
Peter Zijlstrae26af0e2009-09-11 12:31:23 +0200[diff] [blame]13
14/*
Peter Zijlstrae26af0e2009-09-11 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 Zijlstraf8b6d1c2011-07-06 14:20:14 +0200[diff] [blame]19SCHED_FEAT(NEXT_BUDDY, false)
Peter Zijlstrae26af0e2009-09-11 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 Zijlstraf8b6d1c2011-07-06 14:20:14 +0200[diff] [blame]26SCHED_FEAT(LAST_BUDDY, true)
Peter Zijlstrae26af0e2009-09-11 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 Zijlstraf8b6d1c2011-07-06 14:20:14 +0200[diff] [blame]32SCHED_FEAT(CACHE_HOT_BUDDY, true)
Peter Zijlstrae26af0e2009-09-11 12:31:23 +0200[diff] [blame]33
Peter Zijlstra8e6598a2009-09-03 13:20:03 +0200[diff] [blame]34/*
Ingo Molnar8ed92e52012-10-14 14:28:50 +0200[diff] [blame]35 * Allow wakeup-time preemption of the current task:
36 */
37SCHED_FEAT(WAKEUP_PREEMPTION, true)
38
39/*
Nicolas Pitre5d4dfdd2014-05-27 13:50:41 -0400[diff] [blame]40 * Use arch dependent cpu capacity functions
Peter Zijlstra8e6598a2009-09-03 13:20:03 +0200[diff] [blame]41 */
Nicolas Pitre5d4dfdd2014-05-27 13:50:41 -0400[diff] [blame]42SCHED_FEAT(ARCH_CAPACITY, true)
Peter Zijlstra8e6598a2009-09-03 13:20:03 +0200[diff] [blame]43
Peter Zijlstraf8b6d1c2011-07-06 14:20:14 +0200[diff] [blame]44SCHED_FEAT(HRTICK, false)
45SCHED_FEAT(DOUBLE_TICK, false)
46SCHED_FEAT(LB_BIAS, true)
Peter Zijlstrae26af0e2009-09-11 12:31:23 +0200[diff] [blame]47
48/*
Nicolas Pitre5d4dfdd2014-05-27 13:50:41 -0400[diff] [blame]49 * Decrement CPU capacity based on time not spent running tasks
Venkatesh Pallipadiaa483802010-10-04 17:03:22 -0700[diff] [blame]50 */
Nicolas Pitre5d4dfdd2014-05-27 13:50:41 -0400[diff] [blame]51SCHED_FEAT(NONTASK_CAPACITY, true)
Peter Zijlstra317f3942011-04-05 17:23:58 +0200[diff] [blame]52
53/*
54 * Queue remote wakeups on the target CPU and process them
55 * using the scheduler IPI. Reduces rq->lock contention/bounces.
56 */
Peter Zijlstraf8b6d1c2011-07-06 14:20:14 +0200[diff] [blame]57SCHED_FEAT(TTWU_QUEUE, true)
Peter Zijlstrae3589f62011-07-15 10:35:52 +0200[diff] [blame]58
Steven Rostedtb6366f02015-03-18 14:49:46 -0400[diff] [blame^]59#ifdef HAVE_RT_PUSH_IPI
60/*
61 * In order to avoid a thundering herd attack of CPUs that are
62 * lowering their priorities at the same time, and there being
63 * a single CPU that has an RT task that can migrate and is waiting
64 * to run, where the other CPUs will try to take that CPUs
65 * rq lock and possibly create a large contention, sending an
66 * IPI to that CPU and let that CPU push the RT task to where
67 * it should go may be a better scenario.
68 */
69SCHED_FEAT(RT_PUSH_IPI, true)
70#endif
71
Peter Zijlstraf8b6d1c2011-07-06 14:20:14 +0200[diff] [blame]72SCHED_FEAT(FORCE_SD_OVERLAP, false)
73SCHED_FEAT(RT_RUNTIME_SHARE, true)
Peter Zijlstraeb953082012-04-17 13:38:40 +0200[diff] [blame]74SCHED_FEAT(LB_MIN, false)
Peter Zijlstracbee9f82012-10-25 14:16:43 +0200[diff] [blame]75
76/*
Mel Gorman1a687c22012-11-22 11:16:36 +0000[diff] [blame]77 * Apply the automatic NUMA scheduling policy. Enabled automatically
78 * at runtime if running on a NUMA machine. Can be controlled via
Mel Gormanb726b7d2013-10-07 11:28:53 +0100[diff] [blame]79 * numa_balancing=
Peter Zijlstracbee9f82012-10-25 14:16:43 +0200[diff] [blame]80 */
81#ifdef CONFIG_NUMA_BALANCING
Mel Gorman1a687c22012-11-22 11:16:36 +0000[diff] [blame]82SCHED_FEAT(NUMA, false)
Mel Gorman3a7053b2013-10-07 11:29:00 +0100[diff] [blame]83
84/*
85 * NUMA_FAVOUR_HIGHER will favor moving tasks towards nodes where a
86 * higher number of hinting faults are recorded during active load
87 * balancing.
88 */
89SCHED_FEAT(NUMA_FAVOUR_HIGHER, true)
Mel Gorman7a0f3082013-10-07 11:29:01 +0100[diff] [blame]90
91/*
92 * NUMA_RESIST_LOWER will resist moving tasks towards nodes where a
93 * lower number of hinting faults have been recorded. As this has
94 * the potential to prevent a task ever migrating to a new node
95 * due to CPU overload it is disabled by default.
96 */
97SCHED_FEAT(NUMA_RESIST_LOWER, false)
Peter Zijlstracbee9f82012-10-25 14:16:43 +0200[diff] [blame]98#endif