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sched: Restore __cpu_power to a straight sum of power
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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>
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Peter Zijlstra authored and Ingo Molnar committed Sep 4, 2009
1 parent 9aa55fb commit f93e65c
Showing 1 changed file with 12 additions and 16 deletions.
28 changes: 12 additions & 16 deletions kernel/sched.c
Original file line number Diff line number Diff line change
Expand Up @@ -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);

Expand All @@ -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 {
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