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Subject[PATCH 3/3] sched,numa: use effective_load to balance NUMA loads
Date
From: Rik van Riel <riel@redhat.com>

When CONFIG_FAIR_GROUP_SCHED is enabled, the load that a task places
on a CPU is determined by the group the task is in. This is conveniently
calculated for us by effective_load(), which task_numa_compare should
use.

The active groups on the source and destination CPU can be different,
so the calculation needs to be done separately for each CPU.

Signed-off-by: Rik van Riel <riel@redhat.com>
---
kernel/sched/fair.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 976dd73..aafc37c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1151,6 +1151,7 @@ static void task_numa_compare(struct task_numa_env *env,
struct rq *src_rq = cpu_rq(env->src_cpu);
struct rq *dst_rq = cpu_rq(env->dst_cpu);
struct task_struct *cur;
+ struct task_group *tg;
long src_load, dst_load;
long load;
long imp = (groupimp > 0) ? groupimp : taskimp;
@@ -1225,14 +1226,21 @@ static void task_numa_compare(struct task_numa_env *env,
* In the overloaded case, try and keep the load balanced.
*/
balance:
+ src_load = env->src_stats.load;
+ dst_load = env->dst_stats.load;
+
+ /* Calculate the effect of moving env->p from src to dst. */
load = task_h_load(env->p);
- dst_load = env->dst_stats.load + load;
- src_load = env->src_stats.load - load;
+ tg = task_group(env->p);
+ src_load += effective_load(tg, env->src_cpu, -load, -load);
+ dst_load += effective_load(tg, env->dst_cpu, load, load);

if (cur) {
+ /* Cur moves in the opposite direction. */
load = task_h_load(cur);
- dst_load -= load;
- src_load += load;
+ tg = task_group(cur);
+ src_load += effective_load(tg, env->src_cpu, load, load);
+ dst_load += effective_load(tg, env->dst_cpu, -load, -load);
}

if (load_too_imbalanced(src_load, dst_load, env))
--
1.8.5.3


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