[RFC PATCH 04/13] sched:Decide group_imb using PJT's metric

[Preeti U Murthy]

Additional parameters for deciding a sched group's imbalance status
which are calculated using the per entity load tracking are used.

Signed-off-by: Preeti U Murthy <pre...@linux.vnet.ibm.com>
---
 kernel/sched/fair.c |   22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 67a916d..77363c6 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3748,6 +3748,7 @@ struct lb_env {
        int                     new_dst_cpu;
        enum cpu_idle_type      idle;
        long                    imbalance;
+       long long               load_imbalance; /* PJT metric equivalent of 
imbalance */
        /* The set of CPUs under consideration for load-balancing */
        struct cpumask          *cpus;
 
@@ -4513,6 +4514,11 @@ static inline void update_sg_lb_stats(struct lb_env *env,
        unsigned long load, max_cpu_load, min_cpu_load;
        unsigned int balance_cpu = -1, first_idle_cpu = 0;
        unsigned long avg_load_per_task = 0;
+
+       /* Decide imb based on PJT's metric */
+       u64 cpu_runnable_load, max_cpu_runnable_load, min_cpu_runnable_load;
+       u64 avg_sg_load_per_task = 0;
+
        int i;
 
        if (local_group)
@@ -4521,6 +4527,8 @@ static inline void update_sg_lb_stats(struct lb_env *env,
        /* Tally up the load of all CPUs in the group */
        max_cpu_load = 0;
        min_cpu_load = ~0UL;
+       max_cpu_runnable_load = 0;
+       min_cpu_runnable_load = ~0ULL;
        max_nr_running = 0;
        min_nr_running = ~0UL;
 
@@ -4545,6 +4553,12 @@ static inline void update_sg_lb_stats(struct lb_env *env,
                        if (min_cpu_load > load)
                                min_cpu_load = load;
 
+                       cpu_runnable_load = cpu_rq(i)->cfs.runnable_load_avg;
+                       if (cpu_runnable_load > max_cpu_runnable_load)
+                               max_cpu_runnable_load = cpu_runnable_load;
+                       if (min_cpu_runnable_load > cpu_runnable_load)
+                               min_cpu_runnable_load = cpu_runnable_load;
+
                        if (nr_running > max_nr_running)
                                max_nr_running = nr_running;
                        if (min_nr_running > nr_running)
@@ -4604,10 +4618,13 @@ static inline void update_sg_lb_stats(struct lb_env 
*env,
         *      normalized nr_running number somewhere that negates
         *      the hierarchy?
         */
-       if (sgs->sum_nr_running)
+       if (sgs->sum_nr_running) {
                avg_load_per_task = sgs->sum_weighted_load / 
sgs->sum_nr_running;
+               avg_sg_load_per_task = sgs->group_cfs_runnable_load / 
sgs->sum_nr_running;
+       }
 
-       if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
+       /* The following decision is made on PJT's metric */
+       if ((max_cpu_runnable_load - min_cpu_runnable_load) >= 
avg_sg_load_per_task &&
            (max_nr_running - min_nr_running) > 1)
                sgs->group_imb = 1;
 
@@ -5047,6 +5064,7 @@ out_balanced:
 
 ret:
        env->imbalance = 0;
+       env->load_imbalance = 0;
        return NULL;
 }
 

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