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 have different CPU capacities spanning all unique CPU
95 * capacity values.
96 *
97 * SHARED_PARENT: Set from the topmost domain down to the first domain where
98 * all available CPU capacities are visible
99 * NEEDS_GROUPS: Per-CPU capacity is asymmetric between groups.
100 */
101SD_FLAG(SD_ASYM_CPUCAPACITY_FULL, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
102
103/*
104 * Domain members share CPU capacity (i.e. SMT)
105 *
106 * SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share
107 * CPU capacity.
108 * NEEDS_GROUPS: Capacity is shared between groups.
109 */
110SD_FLAG(SD_SHARE_CPUCAPACITY, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
111
112/*
113 * Domain members share CPU cluster (LLC tags or L2 cache)
114 *
115 * NEEDS_GROUPS: Clusters are shared between groups.
116 */
117SD_FLAG(SD_CLUSTER, SDF_NEEDS_GROUPS)
118
119/*
120 * Domain members share CPU Last Level Caches
121 *
122 * SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share
123 * the same cache(s).
124 * NEEDS_GROUPS: Caches are shared between groups.
125 */
126SD_FLAG(SD_SHARE_LLC, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
127
128/*
129 * Only a single load balancing instance
130 *
131 * SHARED_PARENT: Set for all NUMA levels above NODE. Could be set from a
132 * different level upwards, but it doesn't change that if a
133 * domain has this flag set, then all of its parents need to have
134 * it too (otherwise the serialization doesn't make sense).
135 * NEEDS_GROUPS: No point in preserving domain if it has a single group.
136 */
137SD_FLAG(SD_SERIALIZE, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
138
139/*
140 * Place busy tasks earlier in the domain
141 *
142 * NEEDS_GROUPS: Load balancing flag.
143 */
144SD_FLAG(SD_ASYM_PACKING, SDF_NEEDS_GROUPS)
145
146/*
147 * Prefer to place tasks in a sibling domain
148 *
149 * Set up until domains start spanning NUMA nodes. Close to being a SHARED_CHILD
150 * flag, but cleared below domains with SD_ASYM_CPUCAPACITY.
151 *
152 * NEEDS_GROUPS: Load balancing flag.
153 */
154SD_FLAG(SD_PREFER_SIBLING, SDF_NEEDS_GROUPS)
155
156/*
157 * Cross-node balancing
158 *
159 * SHARED_PARENT: Set for all NUMA levels above NODE.
160 * NEEDS_GROUPS: No point in preserving domain if it has a single group.
161 */
162SD_FLAG(SD_NUMA, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
163

source code of linux/include/linux/sched/sd_flags.h