On Mon, May 17, 2021 at 07:02:00PM -0700, Suren Baghdasaryan wrote:
> diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
> index cc25a3cff41f..4b8e72640ac9 100644
> --- a/kernel/sched/psi.c
> +++ b/kernel/sched/psi.c
> @@ -148,6 +148,7 @@
> static int psi_bug __read_mostly;
>
> DEFINE_STATIC_KEY_FALSE(psi_disabled);
> +DEFINE_STATIC_KEY_FALSE(psi_cgroups_disabled);
I'm thinking the whole thing will be easier/clearer when you make this:
DEFINE_STATIC_KEY_TRUE(psi_cgroups_enabled);
>
> #ifdef CONFIG_PSI_DEFAULT_DISABLED
> static bool psi_enable;
> @@ -211,6 +212,9 @@ void __init psi_init(void)
> return;
> }
>
> + if (!cgroup_psi_enabled())
> + static_branch_enable(&psi_cgroups_disabled);
if (!cgroup_psi_enabled())
static_branch_disable(&psi_cgroups_enabled);
> +
> psi_period = jiffies_to_nsecs(PSI_FREQ);
> group_init(&psi_system);
> }
> @@ -744,23 +748,23 @@ static void psi_group_change(struct psi_group *group, int cpu,
>
> static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
> {
> + if (*iter == &psi_system)
> + return NULL;
> +
> #ifdef CONFIG_CGROUPS
> + if (!static_branch_likely(&psi_cgroups_disabled)) {
if (static_branch_likely(&psi_cgroups_enabled)) {
> + struct cgroup *cgroup = NULL;
>
> + if (!*iter)
> + cgroup = task->cgroups->dfl_cgrp;
> + else
> + cgroup = cgroup_parent(*iter);
>
> + if (cgroup && cgroup_parent(cgroup)) {
> + *iter = cgroup;
> + return cgroup_psi(cgroup);
> + }
> }
> #endif
> *iter = &psi_system;
> return &psi_system;
But yes, very nice.
