sched: Introduce SD_SHARE_CAP_STATES sched_domain flag

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>
Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>

diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index 9570c3e37e807fa17c3173b87b734606861f656e..4b5f3c3cbb369eeb53b5e98cd6e8afc28ee41d9f 100644 (file)
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -26,6 +26,7 @@
 #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 */
 
 /*
  * Increase resolution of cpu_capacity calculations

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 9e3be1f8f0c8da49d174f5c449a2b4fc8cf1c23c..d01637e618c883d6ac3533628c485b8175b03cb8 100644 (file)
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -166,7 +166,8 @@ static int sd_degenerate(struct sched_domain *sd)
                         SD_SHARE_CPUCAPACITY |
                         SD_ASYM_CPUCAPACITY |
                         SD_SHARE_PKG_RESOURCES |
-                        SD_SHARE_POWERDOMAIN)) {
+                        SD_SHARE_POWERDOMAIN |
+                        SD_SHARE_CAP_STATES)) {
                if (sd->groups != sd->groups->next)
                        return 0;
        }
@@ -199,7 +200,8 @@ 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;
        }
@@ -1134,6 +1136,7 @@ static int sched_domains_curr_level;
  *   SD_NUMA                - describes NUMA topologies
  *   SD_SHARE_POWERDOMAIN   - describes shared power domain
  *   SD_ASYM_CPUCAPACITY    - describes mixed capacity topologies
+ *   SD_SHARE_CAP_STATES    - describes shared capacity states
  *
  * Odd one out, which beside describing the topology has a quirk also
  * prescribes the desired behaviour that goes along with it:
@@ -1146,7 +1149,8 @@ static int sched_domains_curr_level;
         SD_NUMA |                      \
         SD_ASYM_PACKING |              \
         SD_ASYM_CPUCAPACITY |          \
-        SD_SHARE_POWERDOMAIN)
+        SD_SHARE_POWERDOMAIN |         \
+        SD_SHARE_CAP_STATES)
 
 static struct sched_domain *
 sd_init(struct sched_domain_topology_level *tl,