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authorVincent Guittot <vincent.guittot@linaro.org>2022-08-25 15:27:23 +0300
committerPeter Zijlstra <peterz@infradead.org>2022-09-15 17:13:51 +0300
commitb0defa7ae03ecf91b8bfd10ede430cff12fcbd06 (patch)
treed590d068e868d7ce347e237d7e04095a65193388 /kernel/sched
parentfb04563d1cae6f361892b4a339ad92100b1eb0d0 (diff)
downloadlinux-b0defa7ae03ecf91b8bfd10ede430cff12fcbd06.tar.xz
sched/fair: Make sure to try to detach at least one movable task
During load balance, we try at most env->loop_max time to move a task. But it can happen that the loop_max LRU tasks (ie tail of the cfs_tasks list) can't be moved to dst_cpu because of affinity. In this case, loop in the list until we found at least one. The maximum of detached tasks remained the same as before. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220825122726.20819-2-vincent.guittot@linaro.org
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4e5b171b1171..dae3bfae1bc0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8049,8 +8049,12 @@ static int detach_tasks(struct lb_env *env)
p = list_last_entry(tasks, struct task_struct, se.group_node);
env->loop++;
- /* We've more or less seen every task there is, call it quits */
- if (env->loop > env->loop_max)
+ /*
+ * We've more or less seen every task there is, call it quits
+ * unless we haven't found any movable task yet.
+ */
+ if (env->loop > env->loop_max &&
+ !(env->flags & LBF_ALL_PINNED))
break;
/* take a breather every nr_migrate tasks */
@@ -10179,7 +10183,9 @@ more_balance:
if (env.flags & LBF_NEED_BREAK) {
env.flags &= ~LBF_NEED_BREAK;
- goto more_balance;
+ /* Stop if we tried all running tasks */
+ if (env.loop < busiest->nr_running)
+ goto more_balance;
}
/*