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Subject[RFC PATCH 08/16] sched: Introduce SD_SHARE_CAP_STATES sched_domain flag
Date
cpufreq is currently keeping it a secret which cpus are sharing
clock source. The scheduler needs to know about clock domains as well
to become more energy aware. The SD_SHARE_CAP_STATES domain indicates
whether cpus belonging to the domain share capacity states (P-states).

There is no connection with cpufreq (yet). The flag must be set by
the arch specific topology code.

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
---
arch/arm/kernel/topology.c | 3 ++-
include/linux/sched.h | 1 +
kernel/sched/core.c | 10 +++++++---
3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
index 0b9c1e0..c78d497 100644
--- a/arch/arm/kernel/topology.c
+++ b/arch/arm/kernel/topology.c
@@ -383,7 +383,8 @@ static inline const struct sched_energy *cpu_sys_energy(int cpu)

static inline const int cpu_corepower_flags(void)
{
- return SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN;
+ return SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN | \
+ SD_SHARE_CAP_STATES;
}

static struct sched_domain_topology_level arm_topology[] = {
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4eb149b..62d61b5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -877,6 +877,7 @@ enum cpu_idle_type {
#define SD_PREFER_SIBLING 0x1000 /* Prefer to place tasks in a sibling domain */
#define SD_OVERLAP 0x2000 /* sched_domains of this level overlap */
#define SD_NUMA 0x4000 /* cross-node balancing */
+#define SD_SHARE_CAP_STATES 0x8000 /* Domain members share capacity state */

#ifdef CONFIG_SCHED_SMT
static inline const int cpu_smt_flags(void)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 530a348..49b895a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5322,7 +5322,8 @@ static int sd_degenerate(struct sched_domain *sd)
SD_BALANCE_EXEC |
SD_SHARE_CPUPOWER |
SD_SHARE_PKG_RESOURCES |
- SD_SHARE_POWERDOMAIN)) {
+ SD_SHARE_POWERDOMAIN |
+ SD_SHARE_CAP_STATES)) {
if (sd->groups != sd->groups->next)
return 0;
}
@@ -5354,7 +5355,8 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
SD_SHARE_CPUPOWER |
SD_SHARE_PKG_RESOURCES |
SD_PREFER_SIBLING |
- SD_SHARE_POWERDOMAIN);
+ SD_SHARE_POWERDOMAIN |
+ SD_SHARE_CAP_STATES);
if (nr_node_ids == 1)
pflags &= ~SD_SERIALIZE;
}
@@ -6016,6 +6018,7 @@ static int sched_domains_curr_level;
* SD_SHARE_PKG_RESOURCES - describes shared caches
* SD_NUMA - describes NUMA topologies
* SD_SHARE_POWERDOMAIN - describes shared power domain
+ * SD_SHARE_CAP_STATES - describes shared capacity states
*
* Odd one out:
* SD_ASYM_PACKING - describes SMT quirks
@@ -6025,7 +6028,8 @@ static int sched_domains_curr_level;
SD_SHARE_PKG_RESOURCES | \
SD_NUMA | \
SD_ASYM_PACKING | \
- SD_SHARE_POWERDOMAIN)
+ SD_SHARE_POWERDOMAIN | \
+ SD_SHARE_CAP_STATES)

static struct sched_domain *
sd_init(struct sched_domain_topology_level *tl, int cpu)
--
1.7.9.5



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