* [tip:sched/core] sched/fair: Rework and comment the group_capacity code
@ 2013-09-12 18:05 tip-bot for Peter Zijlstra
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From: tip-bot for Peter Zijlstra @ 2013-09-12 18:05 UTC (permalink / raw)
To: linux-tip-commits; +Cc: linux-kernel, hpa, mingo, peterz, tglx
Commit-ID: b37d931685b519cd61a67fbdfe5b04707eb76e32
Gitweb: http://git.kernel.org/tip/b37d931685b519cd61a67fbdfe5b04707eb76e32
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Wed, 28 Aug 2013 11:50:34 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 12 Sep 2013 19:14:44 +0200
sched/fair: Rework and comment the group_capacity code
Pull out the group_capacity computation so that we can more clearly
comment its issues.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-az1hl1ya55k361nkeh9bj0yw@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/fair.c | 32 ++++++++++++++++++++++++--------
1 file changed, 24 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index baba313..218f9c5 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4553,6 +4553,27 @@ static inline int sg_imbalanced(struct sched_group *group)
return group->sgp->imbalance;
}
+/*
+ * Compute the group capacity.
+ *
+ * For now the capacity is simply the number of power units in the group_power.
+ * A power unit represents a full core.
+ *
+ * This has an issue where N*frac(smt_power) >= 1, in that case we'll see extra
+ * 'cores' that aren't actually there.
+ */
+static inline int sg_capacity(struct lb_env *env, struct sched_group *group)
+{
+
+ unsigned int power = group->sgp->power;
+ unsigned int capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE);
+
+ if (!capacity)
+ capacity = fix_small_capacity(env->sd, group);
+
+ return capacity;
+}
+
/**
* update_sg_lb_stats - Update sched_group's statistics for load balancing.
* @env: The load balancing environment.
@@ -4596,16 +4617,11 @@ static inline void update_sg_lb_stats(struct lb_env *env,
if (sgs->sum_nr_running)
sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
- sgs->group_imb = sg_imbalanced(group);
-
- sgs->group_capacity =
- DIV_ROUND_CLOSEST(sgs->group_power, SCHED_POWER_SCALE);
-
- if (!sgs->group_capacity)
- sgs->group_capacity = fix_small_capacity(env->sd, group);
-
sgs->group_weight = group->group_weight;
+ sgs->group_imb = sg_imbalanced(group);
+ sgs->group_capacity = sg_capacity(env, group);
+
if (sgs->group_capacity > sgs->sum_nr_running)
sgs->group_has_capacity = 1;
}
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