diff options
Diffstat (limited to 'kernel/sched/ext.c')
| -rw-r--r-- | kernel/sched/ext.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index fc94048c9a98..cb1ab668e965 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -18,6 +18,12 @@ enum scx_consts { SCX_EXIT_DUMP_DFL_LEN = 32768, SCX_CPUPERF_ONE = SCHED_CAPACITY_SCALE, + + /* + * Iterating all tasks may take a while. Periodically drop + * scx_tasks_lock to avoid causing e.g. CSD and RCU stalls. + */ + SCX_OPS_TASK_ITER_BATCH = 32, }; enum scx_exit_kind { @@ -1273,6 +1279,7 @@ struct scx_task_iter { struct task_struct *locked; struct rq *rq; struct rq_flags rf; + u32 cnt; }; /** @@ -1301,6 +1308,7 @@ static void scx_task_iter_start(struct scx_task_iter *iter) iter->cursor = (struct sched_ext_entity){ .flags = SCX_TASK_CURSOR }; list_add(&iter->cursor.tasks_node, &scx_tasks); iter->locked = NULL; + iter->cnt = 0; } static void __scx_task_iter_rq_unlock(struct scx_task_iter *iter) @@ -1355,14 +1363,21 @@ static void scx_task_iter_stop(struct scx_task_iter *iter) * scx_task_iter_next - Next task * @iter: iterator to walk * - * Visit the next task. See scx_task_iter_start() for details. + * Visit the next task. See scx_task_iter_start() for details. Locks are dropped + * and re-acquired every %SCX_OPS_TASK_ITER_BATCH iterations to avoid causing + * stalls by holding scx_tasks_lock for too long. */ static struct task_struct *scx_task_iter_next(struct scx_task_iter *iter) { struct list_head *cursor = &iter->cursor.tasks_node; struct sched_ext_entity *pos; - lockdep_assert_held(&scx_tasks_lock); + if (!(++iter->cnt % SCX_OPS_TASK_ITER_BATCH)) { + scx_task_iter_unlock(iter); + cpu_relax(); + cond_resched(); + scx_task_iter_relock(iter); + } list_for_each_entry(pos, cursor, tasks_node) { if (&pos->tasks_node == &scx_tasks) |