xref: /openbmc/linux/kernel/sched/features.h (revision 9470114d)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 
3 /*
4  * Using the avg_vruntime, do the right thing and preserve lag across
5  * sleep+wake cycles. EEVDF placement strategy #1, #2 if disabled.
6  */
7 SCHED_FEAT(PLACE_LAG, true)
8 SCHED_FEAT(PLACE_DEADLINE_INITIAL, true)
9 SCHED_FEAT(RUN_TO_PARITY, true)
10 
11 /*
12  * Prefer to schedule the task we woke last (assuming it failed
13  * wakeup-preemption), since its likely going to consume data we
14  * touched, increases cache locality.
15  */
16 SCHED_FEAT(NEXT_BUDDY, false)
17 
18 /*
19  * Consider buddies to be cache hot, decreases the likeliness of a
20  * cache buddy being migrated away, increases cache locality.
21  */
22 SCHED_FEAT(CACHE_HOT_BUDDY, true)
23 
24 /*
25  * Allow wakeup-time preemption of the current task:
26  */
27 SCHED_FEAT(WAKEUP_PREEMPTION, true)
28 
29 SCHED_FEAT(HRTICK, false)
30 SCHED_FEAT(HRTICK_DL, false)
31 SCHED_FEAT(DOUBLE_TICK, false)
32 
33 /*
34  * Decrement CPU capacity based on time not spent running tasks
35  */
36 SCHED_FEAT(NONTASK_CAPACITY, true)
37 
38 #ifdef CONFIG_PREEMPT_RT
39 SCHED_FEAT(TTWU_QUEUE, false)
40 #else
41 
42 /*
43  * Queue remote wakeups on the target CPU and process them
44  * using the scheduler IPI. Reduces rq->lock contention/bounces.
45  */
46 SCHED_FEAT(TTWU_QUEUE, true)
47 #endif
48 
49 /*
50  * When doing wakeups, attempt to limit superfluous scans of the LLC domain.
51  */
52 SCHED_FEAT(SIS_PROP, false)
53 SCHED_FEAT(SIS_UTIL, true)
54 
55 /*
56  * Issue a WARN when we do multiple update_rq_clock() calls
57  * in a single rq->lock section. Default disabled because the
58  * annotations are not complete.
59  */
60 SCHED_FEAT(WARN_DOUBLE_CLOCK, false)
61 
62 #ifdef HAVE_RT_PUSH_IPI
63 /*
64  * In order to avoid a thundering herd attack of CPUs that are
65  * lowering their priorities at the same time, and there being
66  * a single CPU that has an RT task that can migrate and is waiting
67  * to run, where the other CPUs will try to take that CPUs
68  * rq lock and possibly create a large contention, sending an
69  * IPI to that CPU and let that CPU push the RT task to where
70  * it should go may be a better scenario.
71  */
72 SCHED_FEAT(RT_PUSH_IPI, true)
73 #endif
74 
75 SCHED_FEAT(RT_RUNTIME_SHARE, false)
76 SCHED_FEAT(LB_MIN, false)
77 SCHED_FEAT(ATTACH_AGE_LOAD, true)
78 
79 SCHED_FEAT(WA_IDLE, true)
80 SCHED_FEAT(WA_WEIGHT, true)
81 SCHED_FEAT(WA_BIAS, true)
82 
83 /*
84  * UtilEstimation. Use estimated CPU utilization.
85  */
86 SCHED_FEAT(UTIL_EST, true)
87 SCHED_FEAT(UTIL_EST_FASTUP, true)
88 
89 SCHED_FEAT(LATENCY_WARN, false)
90 
91 SCHED_FEAT(HZ_BW, true)
92