Lines Matching +full:no +full:- +full:idle +full:- +full:on +full:- +full:init
1 // SPDX-License-Identifier: GPL-2.0
7 * The idle injection framework provides a way to force CPUs to enter idle
10 * It relies on the smpboot kthreads feature providing common code for CPU
13 * All of the kthreads used for idle injection are created at init time.
15 * Next, the users of the idle injection framework provide a cpumask via
19 * The idle + run duration is specified via separate helpers and that allows
20 * idle injection to be started.
22 * The idle injection kthreads will call play_idle_precise() with the idle
25 * After all of them have been woken up, a timer is set to start the next idle
28 * The timer interrupt handler will wake up the idle injection kthreads for
31 * Idle injection is stopped synchronously and no leftover idle injection
34 * It is up to the user of this framework to provide a lock for higher-level
35 * synchronization to prevent race conditions like starting idle injection
51 * struct idle_inject_thread - task on/off switch structure
52 * @tsk: task injecting the idle cycles
61 * struct idle_inject_device - idle injection data
62 * @timer: idle injection period timer
63 * @idle_duration_us: duration of CPU idle time to inject
66 * @cpumask: mask of CPUs affected by idle injection
80 * idle_inject_wakeup - Wake up idle injection threads
81 * @ii_dev: target idle injection device
83 * Every idle injection task associated with the given idle injection device
84 * and running on an online CPU will be woken up.
91 for_each_cpu_and(cpu, to_cpumask(ii_dev->cpumask), cpu_online_mask) { in idle_inject_wakeup()
93 iit->should_run = 1; in idle_inject_wakeup()
94 wake_up_process(iit->tsk); in idle_inject_wakeup()
99 * idle_inject_timer_fn - idle injection timer function
100 * @timer: idle injection hrtimer
102 * This function is called when the idle injection timer expires. It wakes up
103 * idle injection tasks associated with the timer and they, in turn, invoke
104 * play_idle_precise() to inject a specified amount of CPU idle time.
114 duration_us = READ_ONCE(ii_dev->run_duration_us); in idle_inject_timer_fn()
115 duration_us += READ_ONCE(ii_dev->idle_duration_us); in idle_inject_timer_fn()
125 * idle_inject_fn - idle injection work function
129 * idle time.
142 iit->should_run = 0; in idle_inject_fn()
144 play_idle_precise(READ_ONCE(ii_dev->idle_duration_us) * NSEC_PER_USEC, in idle_inject_fn()
145 READ_ONCE(ii_dev->latency_us) * NSEC_PER_USEC); in idle_inject_fn()
149 * idle_inject_set_duration - idle and run duration update helper
151 * @idle_duration_us: CPU idle time to inject in microseconds
158 WRITE_ONCE(ii_dev->run_duration_us, run_duration_us); in idle_inject_set_duration()
159 WRITE_ONCE(ii_dev->idle_duration_us, idle_duration_us); in idle_inject_set_duration()
164 * idle_inject_get_duration - idle and run duration retrieval helper
166 * @idle_duration_us: memory location to store the current CPU idle time
172 *run_duration_us = READ_ONCE(ii_dev->run_duration_us); in idle_inject_get_duration()
173 *idle_duration_us = READ_ONCE(ii_dev->idle_duration_us); in idle_inject_get_duration()
177 * idle_inject_set_latency - set the maximum latency allowed
178 * @latency_us: set the latency requirement for the idle state
183 WRITE_ONCE(ii_dev->latency_us, latency_us); in idle_inject_set_latency()
187 * idle_inject_start - start idle injections
188 * @ii_dev: idle injection control device structure
190 * The function starts idle injection by first waking up all of the idle
191 * injection kthreads associated with @ii_dev to let them inject CPU idle time
192 * sets up a timer to start the next idle injection period.
194 * Return: -EINVAL if the CPU idle or CPU run time is not set or 0 on success.
198 unsigned int idle_duration_us = READ_ONCE(ii_dev->idle_duration_us); in idle_inject_start()
199 unsigned int run_duration_us = READ_ONCE(ii_dev->run_duration_us); in idle_inject_start()
202 return -EINVAL; in idle_inject_start()
204 pr_debug("Starting injecting idle cycles on CPUs '%*pbl'\n", in idle_inject_start()
205 cpumask_pr_args(to_cpumask(ii_dev->cpumask))); in idle_inject_start()
209 hrtimer_start(&ii_dev->timer, in idle_inject_start()
218 * idle_inject_stop - stops idle injections
219 * @ii_dev: idle injection control device structure
221 * The function stops idle injection and waits for the threads to finish work.
222 * If CPU idle time is being injected when this function runs, then it will
225 * When it returns, there is no more idle injection kthread activity. The
233 pr_debug("Stopping idle injection on CPUs '%*pbl'\n", in idle_inject_stop()
234 cpumask_pr_args(to_cpumask(ii_dev->cpumask))); in idle_inject_stop()
236 hrtimer_cancel(&ii_dev->timer); in idle_inject_stop()
239 * Stopping idle injection requires all of the idle injection kthreads in idle_inject_stop()
249 * goes offline with the should_run flag set so as to prevent its idle in idle_inject_stop()
253 for_each_cpu(cpu, to_cpumask(ii_dev->cpumask)) { in idle_inject_stop()
255 iit->should_run = 0; in idle_inject_stop()
257 wait_task_inactive(iit->tsk, TASK_ANY); in idle_inject_stop()
264 * idle_inject_setup - prepare the current task for idle injection
276 * idle_inject_should_run - function helper for the smpboot API
277 * @cpu: CPU the kthread is running on
286 return iit->should_run; in idle_inject_should_run()
290 * idle_inject_register - initialize idle injection on a set of CPUs
291 * @cpumask: CPUs to be affected by idle injection
293 * This function creates an idle injection control device structure for the
297 * Return: NULL if memory allocation fails, idle injection control device
298 * pointer on success.
309 cpumask_copy(to_cpumask(ii_dev->cpumask), cpumask); in idle_inject_register()
310 hrtimer_init(&ii_dev->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); in idle_inject_register()
311 ii_dev->timer.function = idle_inject_timer_fn; in idle_inject_register()
312 ii_dev->latency_us = UINT_MAX; in idle_inject_register()
314 for_each_cpu(cpu, to_cpumask(ii_dev->cpumask)) { in idle_inject_register()
327 for_each_cpu(cpu_rb, to_cpumask(ii_dev->cpumask)) { in idle_inject_register()
339 * idle_inject_unregister - unregister idle injection control device
340 * @ii_dev: idle injection control device to unregister
342 * The function stops idle injection for the given control device,
352 for_each_cpu(cpu, to_cpumask(ii_dev->cpumask)) in idle_inject_unregister()