The following commit has been merged into the sched/core branch of tip:
Commit-ID: 4ee4ea443a5dc3fc4d8ae338199676eae9d8ef02
Gitweb: https://git.kernel.org/tip/4ee4ea443a5dc3fc4d8ae338199676eae9d8ef02
Author: Valentin Schneider <valentin.schneider@xxxxxxx>
AuthorDate: Mon, 17 Aug 2020 12:29:53 +01:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 19 Aug 2020 10:49:48 +02:00
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: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Valentin Schneider <valentin.schneider@xxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: https://lore.kernel.org/r/20200817113003.20802-8-valentin.schneider@xxxxxxx
---
include/linux/sched/sd_flags.h | 39 +++++++++++++++++++++++----------
include/linux/sched/topology.h | 7 ++++++-
2 files changed, 35 insertions(+), 11 deletions(-)
diff --git a/include/linux/sched/sd_flags.h b/include/linux/sched/sd_flags.h
index c24a45b..ee5cbfc 100644
--- a/include/linux/sched/sd_flags.h
+++ b/include/linux/sched/sd_flags.h
@@ -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
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index 32f602f..2d59ca7 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -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 {
|