need_active_balance uses env->src_cpu which is set only if there is more than 1 task on the run queue. We must set the src_cpu field unconditionnally otherwise the test "env->src_cpu > env->dst_cpu" will always fail if there is only 1 task on the run queue
Signed-off-by: Vincent Guittot vincent.guittot@linaro.org --- kernel/sched/fair.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 81fa536..32938ea 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5044,6 +5044,10 @@ redo:
ld_moved = 0; lb_iterations = 1; + + env.src_cpu = busiest->cpu; + env.src_rq = busiest; + if (busiest->nr_running > 1) { /* * Attempt to move tasks. If find_busiest_group has found @@ -5052,8 +5056,6 @@ redo: * correctly treated as an imbalance. */ env.flags |= LBF_ALL_PINNED; - env.src_cpu = busiest->cpu; - env.src_rq = busiest; env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running);
update_h_load(env.src_cpu);