Lines Matching refs:tick
164 of the kernel and in particular on whether or not the scheduler tick can be
188 .. _idle-cpus-and-tick:
193 The scheduler tick is a timer that triggers periodically in order to implement
201 may not want to give the CPU away voluntarily, however, and the scheduler tick
203 tick, but it is the primary reason for using it.
205 The scheduler tick is problematic from the CPU idle time management perspective,
207 configuration, the length of the tick period is between 1 ms and 10 ms).
208 Thus, if the tick is allowed to trigger on idle CPUs, it will not make sense
210 the tick period length. Moreover, in that case the idle duration of any CPU
211 will never exceed the tick period length and the energy used for entering and
212 exiting idle states due to the tick wakeups on idle CPUs will be wasted.
214 Fortunately, it is not really necessary to allow the tick to trigger on idle
219 tick goes away if the given CPU is idle. Consequently, it is possible to stop
220 the scheduler tick entirely on idle CPUs in principle, even though that may not
223 Whether or not it makes sense to stop the scheduler tick in the idle loop
225 (non-tick) timer due to trigger within the tick range, stopping the tick clearly
228 wakeup within the tick range, stopping the tick is not necessary and it may even
233 order. Now, if the wakeup really occurs shortly, stopping the tick would be a
235 which is expensive. On the other hand, if the tick is stopped and the wakeup
239 tick range, it is better to allow the tick trigger. Otherwise, however, the
240 governor will select a relatively deep idle state, so the tick should be stopped
244 or not to stop the scheduler tick belongs to it. Still, if the tick has been
248 The kernel can be configured to disable stopping the scheduler tick in the idle
252 scheduler tick is disabled, the governor's decisions regarding it are simply
253 ignored by the idle loop code and the tick is never stopped.
255 The systems that run kernels configured to allow the scheduler tick to be
258 which the tick cannot be stopped. If the given system is tickless, it will use
275 that the scheduler tick will be stopped. That time, referred to as the *sleep
333 if it has not decided to `stop the scheduler tick <idle-cpus-and-tick_>`_. That
334 happens if the idle duration predicted by it is less than the tick period and
335 the tick has not been stopped already (in a previous iteration of the idle
361 tick excluded) for that purpose.
365 assumption that the scheduler tick will be stopped (that also is the upper bound
418 it has not decided to `stop the scheduler tick <idle-cpus-and-tick_>`_. That
420 less than the tick period and the tick has not been stopped already (in a