[RFCv5 PATCH 17/46] sched: Introduce SD_SHARE_CAP_STATES sched_domain flag

Morten Rasmussen
2015-07-07T19:01:29Z

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 flag
indicates whether cpus belonging to the sched_domain share capacity
states (P-states).

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

cc: Russell King <linux@arm.linux.org.uk>
cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>

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 5867587..b35d3e5 100644
--- a/arch/arm/kernel/topology.c
+++ b/arch/arm/kernel/topology.c
@@ -276,7 +276,8 @@ void store_cpu_topology(unsigned int cpuid)

static inline 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 c4d0e88..8ac2db8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -985,6 +985,7 @@ extern void wake_up_q(struct wake_q_head *head);
#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 int cpu_smt_flags(void)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e09ded5..b70a5a7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5563,7 +5563,8 @@ static int sd_degenerate(struct sched_domain *sd)
SD_BALANCE_EXEC |
SD_SHARE_CPUCAPACITY |
SD_SHARE_PKG_RESOURCES |
- SD_SHARE_POWERDOMAIN)) {
+ SD_SHARE_POWERDOMAIN |
+ SD_SHARE_CAP_STATES)) {
if (sd->groups != sd->groups->next)
return 0;
}
@@ -5595,7 +5596,8 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
SD_SHARE_CPUCAPACITY |
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;
}
@@ -6256,6 +6258,7 @@ 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
@@ -6265,7 +6268,8 @@ 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)
--
1.9.1