kernel/linux.git/include/linux/cpuidle.h, branch linux-4.20.y

cpuidle: menu: Fix wakeup statistics updates for polling state

2018-10-04T08:23:37+00:00

If the CPU exits the "polling" state due to the time limit in the loop in poll_idle(), this is not a real wakeup and it just means that the "polling" state selection was not adequate. The governor mispredicted short idle duration, but had a more suitable state been selected, the CPU might have spent more time in it. In fact, there is no reason to expect that there would have been a wakeup event earlier than the next timer in that case. Handling such cases as regular wakeups in menu_update() may cause the menu governor to make suboptimal decisions going forward, but ignoring them altogether would not be correct either, because every time menu_select() is invoked, it makes a separate new attempt to predict the idle duration taking distinct time to the closest timer event as input and the outcomes of all those attempts should be recorded. For this reason, make menu_update() always assume that if the "polling" state was exited due to the time limit, the next proper wakeup event for the CPU would be the next timer event (not including the tick). Fixes: a37b969a61c1 "cpuidle: poll_state: Add time limit to poll_idle()" Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel) Reviewed-by: Daniel Lezcano

cpuidle: Remove unnecessary wrapper cpuidle_get_last_residency()

2018-09-18T07:24:44+00:00

cpuidle_get_last_residency() is just a wrapper for retrieving the last_residency member of struct cpuidle_device. It's also weirdly the only wrapper function for accessing cpuidle_* struct member (by my best guess is it could be a leftover from v2.x). Anyhow, since the only two users (the ladder and menu governors) can access dev->last_residency directly, and it's more intuitive to do it that way, let's just get rid of the wrapper. This patch tidies up CPU idle code a bit without functional changes. Signed-off-by: Fieah Lim [ rjw: Changelog cleanup ] Signed-off-by: Rafael J. Wysocki

cpuidle: governors: Consolidate PM QoS handling

2018-05-30T21:13:00+00:00

There is some code duplication related to the PM QoS handling between the existing cpuidle governors, so move that code to a common helper function and call that from the governors. Signed-off-by: Rafael J. Wysocki

cpuidle: Return nohz hint from cpuidle_select()

2018-04-06T07:29:34+00:00

Add a new pointer argument to cpuidle_select() and to the ->select cpuidle governor callback to allow a boolean value indicating whether or not the tick should be stopped before entering the selected state to be returned from there. Make the ladder governor ignore that pointer (to preserve its current behavior) and make the menu governor return 'false" through it if: (1) the idle exit latency is constrained at 0, or (2) the selected state is a polling one, or (3) the expected idle period duration is within the tick period range. In addition to that, the correction factor computations in the menu governor need to take the possibility that the tick may not be stopped into account to avoid artificially small correction factor values. To that end, add a mechanism to record tick wakeups, as suggested by Peter Zijlstra, and use it to modify the menu_update() behavior when tick wakeup occurs. Namely, if the CPU is woken up by the tick and the return value of tick_nohz_get_sleep_length() is not within the tick boundary, the predicted idle duration is likely too short, so make menu_update() try to compensate for that by updating the governor statistics as though the CPU was idle for a long time. Since the value returned through the new argument pointer of cpuidle_select() is not used by its caller yet, this change by itself is not expected to alter the functionality of the code. Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel)

PM: cpuidle/suspend: Add s2idle usage and time state attributes

2018-03-29T11:06:08+00:00

Add a new attribute group called "s2idle" under the sysfs directory of each cpuidle state that supports the ->enter_s2idle callback and put two new attributes, "usage" and "time", into that group to represent the number of times the given state was requested for suspend-to-idle and the total time spent in suspend-to-idle after requesting that state, respectively. That will allow diagnostic information related to suspend-to-idle to be collected without enabling advanced debug features and analyzing dmesg output. Signed-off-by: Rafael J. Wysocki

Merge branches 'pm-cpuidle' and 'pm-opp'

2018-02-15T11:01:53+00:00

* pm-cpuidle: PM: cpuidle: Fix cpuidle_poll_state_init() prototype Documentation/ABI: update cpuidle sysfs documentation * pm-opp: opp: cpu: Replace GFP_ATOMIC with GFP_KERNEL in dev_pm_opp_init_cpufreq_table

PM: cpuidle: Fix cpuidle_poll_state_init() prototype

2018-02-12T10:34:22+00:00

Commit f85942207516 (x86: PM: Make APM idle driver initialize polling state) made apm_init() call cpuidle_poll_state_init(), but that only is defined for CONFIG_CPU_IDLE set, so make the empty stub of it available for CONFIG_CPU_IDLE unset too to fix the resulting build issue. Fixes: f85942207516 (x86: PM: Make APM idle driver initialize polling state) Cc: 4.14+ # 4.14+ Signed-off-by: Rafael J. Wysocki

cpuidle: Add new macro to enter a retention idle state

2018-01-02T13:48:55+00:00

If a CPU is entering a low power idle state where it doesn't lose any context, then there is no need to call cpu_pm_enter()/cpu_pm_exit(). Add a new macro(CPU_PM_CPU_IDLE_ENTER_RETENTION) to be used by cpuidle drivers when they are entering retention state. By not calling cpu_pm_enter and cpu_pm_exit we reduce the latency involved in entering and exiting the retention idle states. CPU_PM_CPU_IDLE_ENTER_RETENTION assumes that no state is lost and hence CPU PM notifiers will not be called. We may need a broader change if we need to support partial retention states effeciently. On ARM64 based Qualcomm Server Platform we measured below overhead for for calling cpu_pm_enter and cpu_pm_exit for retention states. workload: stress --hdd #CPUs --hdd-bytes 32M -t 30 Average overhead of cpu_pm_enter - 1.2us Average overhead of cpu_pm_exit - 3.1us Acked-by: Rafael J. Wysocki Acked-by: Sudeep Holla Signed-off-by: Prashanth Prakash Signed-off-by: Catalin Marinas

Merge branch 'pm-sleep'

2017-09-03T22:06:02+00:00

* pm-sleep: ACPI / PM: Check low power idle constraints for debug only PM / s2idle: Rename platform operations structure PM / s2idle: Rename ->enter_freeze to ->enter_s2idle PM / s2idle: Rename freeze_state enum and related items PM / s2idle: Rename PM_SUSPEND_FREEZE to PM_SUSPEND_TO_IDLE ACPI / PM: Prefer suspend-to-idle over S3 on some systems platform/x86: intel-hid: Wake up Dell Latitude 7275 from suspend-to-idle PM / suspend: Define pr_fmt() in suspend.c PM / suspend: Use mem_sleep_labels[] strings in messages PM / sleep: Put pm_test under CONFIG_PM_SLEEP_DEBUG PM / sleep: Check pm_wakeup_pending() in __device_suspend_noirq() PM / core: Add error argument to dpm_show_time() PM / core: Split dpm_suspend_noirq() and dpm_resume_noirq() PM / s2idle: Rearrange the main suspend-to-idle loop PM / timekeeping: Print debug messages when requested PM / sleep: Mark suspend/hibernation start and finish PM / sleep: Do not print debug messages by default PM / suspend: Export pm_suspend_target_state

cpuidle: Make drivers initialize polling state

2017-08-30T01:06:33+00:00

Make the drivers that want to include the polling state into their states table initialize it explicitly and drop the initialization of it (which in fact is conditional, but that is not obvious from the code) from the core. Signed-off-by: Rafael J. Wysocki Tested-by: Sudeep Holla Acked-by: Daniel Lezcano