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sched/topology: Introduce SD metaflag for flags needing > 1 groups

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In preparation of cleaning up the sd_degenerate*() functions, mark flags
used in sd_degenerate() with the new SDF_NEEDS_GROUPS flag. With this,
build a compile-time mask of those SD flags.

Note that sd_parent_degenerate() uses an extra flag in its mask,
SD_PREFER_SIBLING, which remains singled out for now.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-8-valentin.schneider@arm.com
This commit is contained in:
Valentin Schneider 2020-08-17 12:29:53 +01:00 committed by Ingo Molnar
parent 5b9f8ff7b3
commit 4ee4ea443a
2 changed files with 35 additions and 11 deletions
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39
include/linux/sched/sd_flags.h
View file

@ -8,7 +8,7 @@
#endif
/*
* Expected flag uses
* Hierarchical metaflags
*
* SHARED_CHILD: These flags are meant to be set from the base domain upwards.
* If a domain has this flag set, all of its children should have it set. This
@ -29,29 +29,42 @@
* certain level (e.g. domain starts spanning CPUs outside of the base CPU's
* socket).
*/
#define SDF_SHARED_CHILD 0x1
#define SDF_SHARED_PARENT 0x2
#define SDF_SHARED_CHILD 0x1
#define SDF_SHARED_PARENT 0x2
/*
* Behavioural metaflags
*
* NEEDS_GROUPS: These flags are only relevant if the domain they are set on has
* more than one group. This is usually for balancing flags (load balancing
* involves equalizing a metric between groups), or for flags describing some
* shared resource (which would be shared between groups).
*/
#define SDF_NEEDS_GROUPS 0x4
/*
* Balance when about to become idle
*
* SHARED_CHILD: Set from the base domain up to cpuset.sched_relax_domain_level.
* NEEDS_GROUPS: Load balancing flag.
*/
SD_FLAG(SD_BALANCE_NEWIDLE, SDF_SHARED_CHILD)
SD_FLAG(SD_BALANCE_NEWIDLE, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
/*
* Balance on exec
*
* SHARED_CHILD: Set from the base domain up to the NUMA reclaim level.
* NEEDS_GROUPS: Load balancing flag.
*/
SD_FLAG(SD_BALANCE_EXEC, SDF_SHARED_CHILD)
SD_FLAG(SD_BALANCE_EXEC, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
/*
* Balance on fork, clone
*
* SHARED_CHILD: Set from the base domain up to the NUMA reclaim level.
* NEEDS_GROUPS: Load balancing flag.
*/
SD_FLAG(SD_BALANCE_FORK, SDF_SHARED_CHILD)
SD_FLAG(SD_BALANCE_FORK, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
/*
* Balance on wakeup
@ -69,24 +82,28 @@ SD_FLAG(SD_WAKE_AFFINE, SDF_SHARED_CHILD)
/*
* Domain members have different CPU capacities
*
* NEEDS_GROUPS: Per-CPU capacity is asymmetric between groups.
*/
SD_FLAG(SD_ASYM_CPUCAPACITY, 0)
SD_FLAG(SD_ASYM_CPUCAPACITY, SDF_NEEDS_GROUPS)
/*
* Domain members share CPU capacity (i.e. SMT)
*
* SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share
* CPU capacity.
* CPU capacity.
* NEEDS_GROUPS: Capacity is shared between groups.
*/
SD_FLAG(SD_SHARE_CPUCAPACITY, SDF_SHARED_CHILD)
SD_FLAG(SD_SHARE_CPUCAPACITY, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
/*
* Domain members share CPU package resources (i.e. caches)
*
* SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share
* the same cache(s).
* the same cache(s).
* NEEDS_GROUPS: Caches are shared between groups.
*/
SD_FLAG(SD_SHARE_PKG_RESOURCES, SDF_SHARED_CHILD)
SD_FLAG(SD_SHARE_PKG_RESOURCES, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
/*
* Only a single load balancing instance

7
include/linux/sched/topology.h
View file

@ -25,6 +25,13 @@ enum {
};
#undef SD_FLAG
/* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */
#define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) |
static const unsigned int SD_DEGENERATE_GROUPS_MASK =
#include <linux/sched/sd_flags.h>
0;
#undef SD_FLAG
#ifdef CONFIG_SCHED_DEBUG
#define SD_FLAG(_name, mflags) [__##_name] = { .meta_flags = mflags, .name = #_name },
static const struct {