From: Tejun Heo <tj@kernel.org> mainline inclusion from mainline-v6.12-rc1 commit 0fd55582ed5b55998ea7df371e25ab40e5c098c3 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IDC9YK Reference: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi... -------------------------------- PM operations freeze userspace. Some BPF schedulers have active userspace component and may misbehave as expected across PM events. While the system is frozen, nothing too interesting is happening in terms of scheduling and we can get by just fine with the fallback FIFO behavior. Let's make things easier by always bypassing the BPF scheduler while PM events are in progress. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Vernet <dvernet@meta.com> Signed-off-by: Zicheng Qu <quzicheng@huawei.com> --- kernel/sched/ext.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 6700db944f1b..6804022b6433 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -4830,6 +4830,34 @@ void print_scx_info(const char *log_lvl, struct task_struct *p) runnable_at_buf); } +static int scx_pm_handler(struct notifier_block *nb, unsigned long event, void *ptr) +{ + /* + * SCX schedulers often have userspace components which are sometimes + * involved in critial scheduling paths. PM operations involve freezing + * userspace which can lead to scheduling misbehaviors including stalls. + * Let's bypass while PM operations are in progress. + */ + switch (event) { + case PM_HIBERNATION_PREPARE: + case PM_SUSPEND_PREPARE: + case PM_RESTORE_PREPARE: + scx_ops_bypass(true); + break; + case PM_POST_HIBERNATION: + case PM_POST_SUSPEND: + case PM_POST_RESTORE: + scx_ops_bypass(false); + break; + } + + return NOTIFY_OK; +} + +static struct notifier_block scx_pm_notifier = { + .notifier_call = scx_pm_handler, +}; + void __init init_sched_ext_class(void) { s32 cpu, v; @@ -5734,6 +5762,12 @@ static int __init scx_init(void) return ret; } + ret = register_pm_notifier(&scx_pm_notifier); + if (ret) { + pr_err("sched_ext: Failed to register PM notifier (%d)\n", ret); + return ret; + } + scx_kset = kset_create_and_add("sched_ext", &scx_uevent_ops, kernel_kobj); if (!scx_kset) { pr_err("sched_ext: Failed to create /sys/kernel/sched_ext\n"); -- 2.34.1