sched: Restore __cpu_power to a straight sum of power

cpu_power is supposed to be a representation of the process
capacity of the cpu, not a value to randomly tweak in order to
affect placement.

Remove the placement hacks.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: Gautham R Shenoy <ego@in.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
LKML-Reference: <20090901083825.810860576@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 16 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index da1edc8277d0..584a122b553c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8464,15 +8464,13 @@ static void free_sched_groups(const struct cpumask *cpu_map,
  * there are asymmetries in the topology. If there are asymmetries, group
  * having more cpu_power will pickup more load compared to the group having
  * less cpu_power.
- *
- * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
- * the maximum number of tasks a group can handle in the presence of other idle
- * or lightly loaded groups in the same sched domain.
  */
 static void init_sched_groups_power(int cpu, struct sched_domain *sd)
 {
         struct sched_domain *child;
         struct sched_group *group;
+        long power;
+        int weight;
 
         WARN_ON(!sd || !sd->groups);
 
@@ -8483,22 +8481,20 @@ static void init_sched_groups_power(int cpu, struct sched_domain *sd)
 
         sd->groups->__cpu_power = 0;
 
-        /*
-         * For perf policy, if the groups in child domain share resources
-         * (for example cores sharing some portions of the cache hierarchy
-         * or SMT), then set this domain groups cpu_power such that each group
-         * can handle only one task, when there are other idle groups in the
-         * same sched domain.
-         */
-        if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) &&
-                       (child->flags &
-                        (SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) {
-                sg_inc_cpu_power(sd->groups, SCHED_LOAD_SCALE);
+        if (!child) {
+                power = SCHED_LOAD_SCALE;
+                weight = cpumask_weight(sched_domain_span(sd));
+                /*
+                 * SMT siblings share the power of a single core.
+                 */
+                if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1)
+                        power /= weight;
+                sg_inc_cpu_power(sd->groups, power);
                 return;
         }
 
         /*
-         * add cpu_power of each child group to this groups cpu_power
+         * Add cpu_power of each child group to this groups cpu_power.
          */
         group = child->groups;
         do {