From a761ae85013944d6e007a343c7f24c342ae4dc18 Mon Sep 17 00:00:00 2001 From: Pavankumar Kondeti Date: Thu, 8 Jun 2017 15:19:48 +0530 Subject: sched: Fix the bug in select_best_cpu() that returns -1 as target_cpu select_best_cpu() has previous CPU's cluster bias which overrides the best_cpu with best_sibling_cpu when the power cost is same. When the power table is configured incorrectly or static_cpu_pwr_cost/ static_cluster_pwr_cost tunables are set to a large value, the power_cost() for all candidate CPUs can return INT_MAX. So the stats.min_cost is never changed from it's initial value i.e INT_MAX. In the above scenario, we find stats.best_cpu >= 0 && stats.min_cost = stats.best_sibling_cpu_cost = INT_MAX && stats.best_sibling_cpu_cost = -1 and replace best_cpu with best_sibling_cpu i.e -1. Change-Id: I09829e278e41daaaff959428ff50927aba29104c Signed-off-by: Pavankumar Kondeti --- kernel/sched/fair.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 9abc3e65dbd9..ef00eaf41317 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3240,7 +3240,8 @@ retry: sbc_flag |= SBC_FLAG_IDLE_LEAST_LOADED; } } else if (stats.best_cpu >= 0) { - if (stats.best_cpu != task_cpu(p) && + if (stats.best_sibling_cpu >= 0 && + stats.best_cpu != task_cpu(p) && stats.min_cost == stats.best_sibling_cpu_cost) { stats.best_cpu = stats.best_sibling_cpu; sbc_flag |= SBC_FLAG_BEST_SIBLING; -- cgit v1.2.3