xref: /linux/kernel/sched/features.h (revision 2a2c74b2efcb1a0ca3fdcb5fbb96ad8de6a29177)
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 /*
9  * Place new tasks ahead so that they do not starve already running
10  * tasks
11  */
12 SCHED_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  */
19 SCHED_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  */
26 SCHED_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  */
32 SCHED_FEAT(CACHE_HOT_BUDDY, true)
33 
34 /*
35  * Allow wakeup-time preemption of the current task:
36  */
37 SCHED_FEAT(WAKEUP_PREEMPTION, true)
38 
39 /*
40  * Use arch dependent cpu power functions
41  */
42 SCHED_FEAT(ARCH_POWER, true)
43 
44 SCHED_FEAT(HRTICK, false)
45 SCHED_FEAT(DOUBLE_TICK, false)
46 SCHED_FEAT(LB_BIAS, true)
47 
48 /*
49  * Decrement CPU power based on time not spent running tasks
50  */
51 SCHED_FEAT(NONTASK_POWER, true)
52 
53 /*
54  * Queue remote wakeups on the target CPU and process them
55  * using the scheduler IPI. Reduces rq->lock contention/bounces.
56  */
57 SCHED_FEAT(TTWU_QUEUE, true)
58 
59 SCHED_FEAT(FORCE_SD_OVERLAP, false)
60 SCHED_FEAT(RT_RUNTIME_SHARE, true)
61 SCHED_FEAT(LB_MIN, false)
62 
63 /*
64  * Apply the automatic NUMA scheduling policy. Enabled automatically
65  * at runtime if running on a NUMA machine. Can be controlled via
66  * numa_balancing=
67  */
68 #ifdef CONFIG_NUMA_BALANCING
69 SCHED_FEAT(NUMA,	false)
70 
71 /*
72  * NUMA_FAVOUR_HIGHER will favor moving tasks towards nodes where a
73  * higher number of hinting faults are recorded during active load
74  * balancing.
75  */
76 SCHED_FEAT(NUMA_FAVOUR_HIGHER, true)
77 
78 /*
79  * NUMA_RESIST_LOWER will resist moving tasks towards nodes where a
80  * lower number of hinting faults have been recorded. As this has
81  * the potential to prevent a task ever migrating to a new node
82  * due to CPU overload it is disabled by default.
83  */
84 SCHED_FEAT(NUMA_RESIST_LOWER, false)
85 #endif
86