sched/fair: Fix asym packing to select correct CPU

[mirror_ubuntu-bionic-kernel.git] / kernel / sched / fair.c

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b8cc1c35cd7c188e3d7cd1c3bb990fa286ff53e0..6e371f43fc804b0c6598e8d98e401f5d898c45b5 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6679,6 +6679,9 @@ static bool update_sd_pick_busiest(struct lb_env *env,
        if (!(env->sd->flags & SD_ASYM_PACKING))
                return true;
 
+       /* No ASYM_PACKING if target cpu is already busy */
+       if (env->idle == CPU_NOT_IDLE)
+               return true;
        /*
         * ASYM_PACKING needs to move all the work to the lowest
         * numbered CPUs in the group, therefore mark all groups
@@ -6688,7 +6691,8 @@ static bool update_sd_pick_busiest(struct lb_env *env,
                if (!sds->busiest)
                        return true;
 
-               if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
+               /* Prefer to move from highest possible cpu's work */
+               if (group_first_cpu(sds->busiest) < group_first_cpu(sg))
                        return true;
        }
 
@@ -6834,6 +6838,9 @@ static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
        if (!(env->sd->flags & SD_ASYM_PACKING))
                return 0;
 
+       if (env->idle == CPU_NOT_IDLE)
+               return 0;
+
        if (!sds->busiest)
                return 0;
 
@@ -7026,8 +7033,7 @@ static struct sched_group *find_busiest_group(struct lb_env *env)
        busiest = &sds.busiest_stat;
 
        /* ASYM feature bypasses nice load balance check */
-       if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
-           check_asym_packing(env, &sds))
+       if (check_asym_packing(env, &sds))
                return sds.busiest;
 
        /* There is no busy sibling group to pull tasks from */