Commit 4ee4ea44 authored by Valentin Schneider's avatar Valentin Schneider Committed by Ingo Molnar
Browse files

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



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: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarValentin Schneider <valentin.schneider@arm.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-8-valentin.schneider@arm.com
parent 5b9f8ff7

include/linux/sched/sd_flags.h

+28 −11
Original line number Diff line number Diff line
@@ -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
@@ -32,26 +32,39 @@ 
#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.

 * 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).

 * 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

include/linux/sched/topology.h

+7 −0
Original line number Diff line number Diff line
@@ -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 {

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