psi: eliminate kthread_worker from psi trigger scheduling mechanism

Each psi group requires a dedicated kthread_delayed_work and kthread_worker. Since no other work can be performed using psi_group's kthread_worker, the same result can be obtained using a task_struct and a timer directly. This makes psi triggering simpler by removing lists and locks involved with kthread_worker usage and eliminates the need for poll_scheduled atomic use in the hot path.

Suren Baghdasaryan committed 6 years ago

Commit 461daba1 parent f4291df2 files · +68 −52Browse files

Showing the changes to include/linux (1 of 2 files). Show all

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include/linux/psi_types.h+4−3

@@ -153,9 +153,10 @@ struct psi_group { · 152 unmodified lines
153	153	unsigned long avg[NR_PSI_STATES - 1][3];
154	154
155	155	/* Monitor work control */
156		− atomic_t poll_scheduled;
157		− struct kthread_worker __rcu *poll_kworker;
158		− struct kthread_delayed_work poll_work;
	156	+ struct task_struct __rcu *poll_task;
	157	+ struct timer_list poll_timer;
	158	+ wait_queue_head_t poll_wait;
	159	+ atomic_t poll_wakeup;
159	160
160	161	/* Protects data used by the monitor */
161	162	struct mutex trigger_lock;