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review.trustedfirmware.org / hafnium / third_party / linux.git / 157378f43faad830e4aa3815bde5fa9f9a9f5be6 / . / include / linux / sched / sd_flags.h
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Olivier Deprez157378f2022-04-04 15:47:50 +0200[diff] [blame^]1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * sched-domains (multiprocessor balancing) flag declarations.
4 */
5
6#ifndef SD_FLAG
7# error "Incorrect import of SD flags definitions"
8#endif
9
10/*
11 * Hierarchical metaflags
12 *
13 * SHARED_CHILD: These flags are meant to be set from the base domain upwards.
14 * If a domain has this flag set, all of its children should have it set. This
15 * is usually because the flag describes some shared resource (all CPUs in that
16 * domain share the same resource), or because they are tied to a scheduling
17 * behaviour that we want to disable at some point in the hierarchy for
18 * scalability reasons.
19 *
20 * In those cases it doesn't make sense to have the flag set for a domain but
21 * not have it in (some of) its children: sched domains ALWAYS span their child
22 * domains, so operations done with parent domains will cover CPUs in the lower
23 * child domains.
24 *
25 *
26 * SHARED_PARENT: These flags are meant to be set from the highest domain
27 * downwards. If a domain has this flag set, all of its parents should have it
28 * set. This is usually for topology properties that start to appear above a
29 * certain level (e.g. domain starts spanning CPUs outside of the base CPU's
30 * socket).
31 */
32#define SDF_SHARED_CHILD 0x1
33#define SDF_SHARED_PARENT 0x2
34
35/*
36 * Behavioural metaflags
37 *
38 * NEEDS_GROUPS: These flags are only relevant if the domain they are set on has
39 * more than one group. This is usually for balancing flags (load balancing
40 * involves equalizing a metric between groups), or for flags describing some
41 * shared resource (which would be shared between groups).
42 */
43#define SDF_NEEDS_GROUPS 0x4
44
45/*
46 * Balance when about to become idle
47 *
48 * SHARED_CHILD: Set from the base domain up to cpuset.sched_relax_domain_level.
49 * NEEDS_GROUPS: Load balancing flag.
50 */
51SD_FLAG(SD_BALANCE_NEWIDLE, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
52
53/*
54 * Balance on exec
55 *
56 * SHARED_CHILD: Set from the base domain up to the NUMA reclaim level.
57 * NEEDS_GROUPS: Load balancing flag.
58 */
59SD_FLAG(SD_BALANCE_EXEC, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
60
61/*
62 * Balance on fork, clone
63 *
64 * SHARED_CHILD: Set from the base domain up to the NUMA reclaim level.
65 * NEEDS_GROUPS: Load balancing flag.
66 */
67SD_FLAG(SD_BALANCE_FORK, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
68
69/*
70 * Balance on wakeup
71 *
72 * SHARED_CHILD: Set from the base domain up to cpuset.sched_relax_domain_level.
73 * NEEDS_GROUPS: Load balancing flag.
74 */
75SD_FLAG(SD_BALANCE_WAKE, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
76
77/*
78 * Consider waking task on waking CPU.
79 *
80 * SHARED_CHILD: Set from the base domain up to the NUMA reclaim level.
81 */
82SD_FLAG(SD_WAKE_AFFINE, SDF_SHARED_CHILD)
83
84/*
85 * Domain members have different CPU capacities
86 *
87 * SHARED_PARENT: Set from the topmost domain down to the first domain where
88 * asymmetry is detected.
89 * NEEDS_GROUPS: Per-CPU capacity is asymmetric between groups.
90 */
91SD_FLAG(SD_ASYM_CPUCAPACITY, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
92
93/*
94 * Domain members share CPU capacity (i.e. SMT)
95 *
96 * SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share
97 * CPU capacity.
98 * NEEDS_GROUPS: Capacity is shared between groups.
99 */
100SD_FLAG(SD_SHARE_CPUCAPACITY, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
101
102/*
103 * Domain members share CPU package resources (i.e. caches)
104 *
105 * SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share
106 * the same cache(s).
107 * NEEDS_GROUPS: Caches are shared between groups.
108 */
109SD_FLAG(SD_SHARE_PKG_RESOURCES, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
110
111/*
112 * Only a single load balancing instance
113 *
114 * SHARED_PARENT: Set for all NUMA levels above NODE. Could be set from a
115 * different level upwards, but it doesn't change that if a
116 * domain has this flag set, then all of its parents need to have
117 * it too (otherwise the serialization doesn't make sense).
118 * NEEDS_GROUPS: No point in preserving domain if it has a single group.
119 */
120SD_FLAG(SD_SERIALIZE, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
121
122/*
123 * Place busy tasks earlier in the domain
124 *
125 * SHARED_CHILD: Usually set on the SMT level. Technically could be set further
126 * up, but currently assumed to be set from the base domain
127 * upwards (see update_top_cache_domain()).
128 * NEEDS_GROUPS: Load balancing flag.
129 */
130SD_FLAG(SD_ASYM_PACKING, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
131
132/*
133 * Prefer to place tasks in a sibling domain
134 *
135 * Set up until domains start spanning NUMA nodes. Close to being a SHARED_CHILD
136 * flag, but cleared below domains with SD_ASYM_CPUCAPACITY.
137 *
138 * NEEDS_GROUPS: Load balancing flag.
139 */
140SD_FLAG(SD_PREFER_SIBLING, SDF_NEEDS_GROUPS)
141
142/*
143 * sched_groups of this level overlap
144 *
145 * SHARED_PARENT: Set for all NUMA levels above NODE.
146 * NEEDS_GROUPS: Overlaps can only exist with more than one group.
147 */
148SD_FLAG(SD_OVERLAP, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
149
150/*
151 * Cross-node balancing
152 *
153 * SHARED_PARENT: Set for all NUMA levels above NODE.
154 * NEEDS_GROUPS: No point in preserving domain if it has a single group.
155 */
156SD_FLAG(SD_NUMA, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)