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5f4a1c4ea4
There would be no point in preserving a sched_domain with a single group just because it has this flag set. Add it to SD_DEGENERATE_GROUPS_MASK. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: https://lore.kernel.org/r/20200817113003.20802-17-valentin.schneider@arm.com
156 lines
5 KiB
C
156 lines
5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* sched-domains (multiprocessor balancing) flag declarations.
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*/
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#ifndef SD_FLAG
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# error "Incorrect import of SD flags definitions"
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#endif
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/*
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* Hierarchical metaflags
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*
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* SHARED_CHILD: These flags are meant to be set from the base domain upwards.
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* If a domain has this flag set, all of its children should have it set. This
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* is usually because the flag describes some shared resource (all CPUs in that
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* domain share the same resource), or because they are tied to a scheduling
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* behaviour that we want to disable at some point in the hierarchy for
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* scalability reasons.
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*
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* In those cases it doesn't make sense to have the flag set for a domain but
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* not have it in (some of) its children: sched domains ALWAYS span their child
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* domains, so operations done with parent domains will cover CPUs in the lower
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* child domains.
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*
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*
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* SHARED_PARENT: These flags are meant to be set from the highest domain
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* downwards. If a domain has this flag set, all of its parents should have it
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* set. This is usually for topology properties that start to appear above a
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* certain level (e.g. domain starts spanning CPUs outside of the base CPU's
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* socket).
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*/
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#define SDF_SHARED_CHILD 0x1
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#define SDF_SHARED_PARENT 0x2
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/*
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* Behavioural metaflags
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*
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* NEEDS_GROUPS: These flags are only relevant if the domain they are set on has
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* more than one group. This is usually for balancing flags (load balancing
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* involves equalizing a metric between groups), or for flags describing some
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* shared resource (which would be shared between groups).
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*/
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#define SDF_NEEDS_GROUPS 0x4
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/*
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* Balance when about to become idle
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*
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* SHARED_CHILD: Set from the base domain up to cpuset.sched_relax_domain_level.
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* NEEDS_GROUPS: Load balancing flag.
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*/
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SD_FLAG(SD_BALANCE_NEWIDLE, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
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/*
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* Balance on exec
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*
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* SHARED_CHILD: Set from the base domain up to the NUMA reclaim level.
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* NEEDS_GROUPS: Load balancing flag.
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*/
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SD_FLAG(SD_BALANCE_EXEC, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
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/*
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* Balance on fork, clone
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*
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* SHARED_CHILD: Set from the base domain up to the NUMA reclaim level.
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* NEEDS_GROUPS: Load balancing flag.
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*/
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SD_FLAG(SD_BALANCE_FORK, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
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/*
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* Balance on wakeup
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*
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* SHARED_CHILD: Set from the base domain up to cpuset.sched_relax_domain_level.
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* NEEDS_GROUPS: Load balancing flag.
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*/
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SD_FLAG(SD_BALANCE_WAKE, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
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/*
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* Consider waking task on waking CPU.
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*
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* SHARED_CHILD: Set from the base domain up to the NUMA reclaim level.
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*/
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SD_FLAG(SD_WAKE_AFFINE, SDF_SHARED_CHILD)
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/*
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* Domain members have different CPU capacities
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*
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* SHARED_PARENT: Set from the topmost domain down to the first domain where
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* asymmetry is detected.
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* NEEDS_GROUPS: Per-CPU capacity is asymmetric between groups.
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*/
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SD_FLAG(SD_ASYM_CPUCAPACITY, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
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/*
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* Domain members share CPU capacity (i.e. SMT)
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*
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* SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share
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* CPU capacity.
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* NEEDS_GROUPS: Capacity is shared between groups.
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*/
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SD_FLAG(SD_SHARE_CPUCAPACITY, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
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/*
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* Domain members share CPU package resources (i.e. caches)
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*
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* SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share
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* the same cache(s).
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* NEEDS_GROUPS: Caches are shared between groups.
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*/
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SD_FLAG(SD_SHARE_PKG_RESOURCES, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
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/*
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* Only a single load balancing instance
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*
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* SHARED_PARENT: Set for all NUMA levels above NODE. Could be set from a
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* different level upwards, but it doesn't change that if a
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* domain has this flag set, then all of its parents need to have
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* it too (otherwise the serialization doesn't make sense).
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* NEEDS_GROUPS: No point in preserving domain if it has a single group.
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*/
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SD_FLAG(SD_SERIALIZE, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
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/*
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* Place busy tasks earlier in the domain
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*
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* SHARED_CHILD: Usually set on the SMT level. Technically could be set further
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* up, but currently assumed to be set from the base domain
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* upwards (see update_top_cache_domain()).
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* NEEDS_GROUPS: Load balancing flag.
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*/
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SD_FLAG(SD_ASYM_PACKING, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
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/*
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* Prefer to place tasks in a sibling domain
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*
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* Set up until domains start spanning NUMA nodes. Close to being a SHARED_CHILD
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* flag, but cleared below domains with SD_ASYM_CPUCAPACITY.
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*
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* NEEDS_GROUPS: Load balancing flag.
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*/
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SD_FLAG(SD_PREFER_SIBLING, SDF_NEEDS_GROUPS)
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/*
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* sched_groups of this level overlap
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*
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* SHARED_PARENT: Set for all NUMA levels above NODE.
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* NEEDS_GROUPS: Overlaps can only exist with more than one group.
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*/
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SD_FLAG(SD_OVERLAP, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
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/*
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* Cross-node balancing
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*
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* SHARED_PARENT: Set for all NUMA levels above NODE.
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* NEEDS_GROUPS: No point in preserving domain if it has a single group.
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*/
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SD_FLAG(SD_NUMA, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
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