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psi: eliminate kthread_worker from psi trigger scheduling mechanism

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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.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200528195442.190116-1-surenb@google.com
This commit is contained in:
Suren Baghdasaryan 2020-05-28 12:54:42 -07:00 • committed by Peter Zijlstra
parent f4291df103
commit 461daba06b
2 changed files with 68 additions and 52 deletions
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7
include/linux/psi_types.h
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@ -153,9 +153,10 @@ struct psi_group {
unsigned long avg[NR_PSI_STATES - 1][3];
/* Monitor work control */
atomic_t poll_scheduled;
struct kthread_worker __rcu *poll_kworker;
struct kthread_delayed_work poll_work;
struct task_struct __rcu *poll_task;
struct timer_list poll_timer;
wait_queue_head_t poll_wait;
atomic_t poll_wakeup;
/* Protects data used by the monitor */
struct mutex trigger_lock;