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Date: Tue, 18 Jun 2013 21:04:17 +0800
From: Lei Wen <leiwen@...vell.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
<mingo@...hat.com>, <leiwen@...vell.com>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH v4 2/4] sched: scale the busy and this queue's per-task load before compare
Since for max_load and this_load, they are the value that already be
scaled. It is not reasonble to get a minimum value between the scaled
and non-scaled value, like below example.
min(sds->busiest_load_per_task, sds->max_load);
Also add comment over in what condition, there would be cpu power gain
in move the load.
Signed-off-by: Lei Wen <leiwen@...vell.com>
---
kernel/sched/fair.c | 55 +++++++++++++++++++++++++++++++++++----------------
1 file changed, 38 insertions(+), 17 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 28052fa..fd9cbee 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4686,16 +4686,19 @@ static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
* load balancing.
* @env: The load balancing environment.
* @sds: Statistics of the sched_domain whose imbalance is to be calculated.
+ * @scaled_busiest_load_per_task: per calculated busist queue average load
*/
static inline
-void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
+void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds,
+ unsigned long scaled_busy_load_per_task)
{
unsigned long tmp, pwr_now = 0, pwr_move = 0;
+ unsigned long scaled_this_load_per_task;
unsigned int imbn = 2;
- unsigned long scaled_busy_load_per_task;
if (sds->this_nr_running) {
sds->this_load_per_task /= sds->this_nr_running;
+
if (sds->busiest_load_per_task >
sds->this_load_per_task)
imbn = 1;
@@ -4704,9 +4707,10 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
cpu_avg_load_per_task(env->dst_cpu);
}
- scaled_busy_load_per_task = sds->busiest_load_per_task
- * SCHED_POWER_SCALE;
- scaled_busy_load_per_task /= sds->busiest->sgp->power;
+ /* Scale this_load_per_task to local power not related */
+ scaled_this_load_per_task = sds->this_load_per_task
+ << SCHED_POWER_SHIFT;
+ scaled_this_load_per_task /= sds->this->sgp->power;
if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
(scaled_busy_load_per_task * imbn)) {
@@ -4721,28 +4725,35 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
*/
pwr_now += sds->busiest->sgp->power *
- min(sds->busiest_load_per_task, sds->max_load);
+ min(scaled_busy_load_per_task, sds->max_load);
pwr_now += sds->this->sgp->power *
- min(sds->this_load_per_task, sds->this_load);
+ min(scaled_this_load_per_task, sds->this_load);
pwr_now /= SCHED_POWER_SCALE;
/* Amount of load we'd subtract */
if (sds->max_load > scaled_busy_load_per_task) {
pwr_move += sds->busiest->sgp->power *
- min(sds->busiest_load_per_task,
+ min(scaled_busy_load_per_task,
sds->max_load - scaled_busy_load_per_task);
- tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
- sds->this->sgp->power;
+ tmp = scaled_busy_load_per_task;
} else
- tmp = (sds->max_load * sds->busiest->sgp->power) /
- sds->this->sgp->power;
+ tmp = sds->max_load;
+ /* Scale to this queue from busiest queue */
+ tmp = (tmp * sds->busiest->sgp->power) /
+ sds->this->sgp->power;
/* Amount of load we'd add */
pwr_move += sds->this->sgp->power *
- min(sds->this_load_per_task, sds->this_load + tmp);
+ min(scaled_this_load_per_task, sds->this_load + tmp);
pwr_move /= SCHED_POWER_SCALE;
/* Move if we gain throughput */
+ /*
+ * The only possibilty for below statement be true, is:
+ * sds->max_load is larger than sds->busiest_load_per_task, while,
+ * sds->busiest_load_per_task is larger than sds->this_load plus by
+ * the scaled sds->busiest_load_per_task moved into this queue
+ */
if (pwr_move > pwr_now)
env->imbalance = sds->busiest_load_per_task;
}
@@ -4756,11 +4767,21 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
{
unsigned long max_pull, load_above_capacity = ~0UL;
+ unsigned long scaled_busy_load_per_task;
sds->busiest_load_per_task /= sds->busiest_nr_running;
+
+ /* Scale busiest_load_per_task to local power not related */
+ scaled_busy_load_per_task = sds->busiest_load_per_task
+ << SCHED_POWER_SHIFT;
+ scaled_busy_load_per_task /= sds->busiest->sgp->power;
+
if (sds->group_imb) {
- sds->busiest_load_per_task =
- min(sds->busiest_load_per_task, sds->avg_load);
+ scaled_busy_load_per_task =
+ min(scaled_busy_load_per_task, sds->avg_load);
+ sds->busiest_load_per_task = scaled_busy_load_per_task
+ * sds->busiest->sgp->power;
+ sds->busiest_load_per_task >>= SCHED_POWER_SHIFT;
}
/*
@@ -4770,7 +4791,7 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
*/
if (sds->max_load < sds->avg_load) {
env->imbalance = 0;
- return fix_small_imbalance(env, sds);
+ return fix_small_imbalance(env, sds, scaled_busy_load_per_task);
}
if (!sds->group_imb) {
@@ -4809,7 +4830,7 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* moved
*/
if (env->imbalance < sds->busiest_load_per_task)
- return fix_small_imbalance(env, sds);
+ return fix_small_imbalance(env, sds, scaled_busy_load_per_task);
}
--
1.7.10.4
--
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