mirror of https://gitee.com/openkylin/linux.git
97 lines
3.4 KiB
Plaintext
97 lines
3.4 KiB
Plaintext
|
|
Subsystem Trace Points: power
|
|
|
|
The power tracing system captures events related to power transitions
|
|
within the kernel. Broadly speaking there are three major subheadings:
|
|
|
|
o Power state switch which reports events related to suspend (S-states),
|
|
cpuidle (C-states) and cpufreq (P-states)
|
|
o System clock related changes
|
|
o Power domains related changes and transitions
|
|
|
|
This document describes what each of the tracepoints is and why they
|
|
might be useful.
|
|
|
|
Cf. include/trace/events/power.h for the events definitions.
|
|
|
|
1. Power state switch events
|
|
============================
|
|
|
|
1.1 Trace API
|
|
-----------------
|
|
|
|
A 'cpu' event class gathers the CPU-related events: cpuidle and
|
|
cpufreq.
|
|
|
|
cpu_idle "state=%lu cpu_id=%lu"
|
|
cpu_frequency "state=%lu cpu_id=%lu"
|
|
|
|
A suspend event is used to indicate the system going in and out of the
|
|
suspend mode:
|
|
|
|
machine_suspend "state=%lu"
|
|
|
|
|
|
Note: the value of '-1' or '4294967295' for state means an exit from the current state,
|
|
i.e. trace_cpu_idle(4, smp_processor_id()) means that the system
|
|
enters the idle state 4, while trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id())
|
|
means that the system exits the previous idle state.
|
|
|
|
The event which has 'state=4294967295' in the trace is very important to the user
|
|
space tools which are using it to detect the end of the current state, and so to
|
|
correctly draw the states diagrams and to calculate accurate statistics etc.
|
|
|
|
2. Clocks events
|
|
================
|
|
The clock events are used for clock enable/disable and for
|
|
clock rate change.
|
|
|
|
clock_enable "%s state=%lu cpu_id=%lu"
|
|
clock_disable "%s state=%lu cpu_id=%lu"
|
|
clock_set_rate "%s state=%lu cpu_id=%lu"
|
|
|
|
The first parameter gives the clock name (e.g. "gpio1_iclk").
|
|
The second parameter is '1' for enable, '0' for disable, the target
|
|
clock rate for set_rate.
|
|
|
|
3. Power domains events
|
|
=======================
|
|
The power domain events are used for power domains transitions
|
|
|
|
power_domain_target "%s state=%lu cpu_id=%lu"
|
|
|
|
The first parameter gives the power domain name (e.g. "mpu_pwrdm").
|
|
The second parameter is the power domain target state.
|
|
|
|
4. PM QoS events
|
|
================
|
|
The PM QoS events are used for QoS add/update/remove request and for
|
|
target/flags update.
|
|
|
|
pm_qos_add_request "pm_qos_class=%s value=%d"
|
|
pm_qos_update_request "pm_qos_class=%s value=%d"
|
|
pm_qos_remove_request "pm_qos_class=%s value=%d"
|
|
pm_qos_update_request_timeout "pm_qos_class=%s value=%d, timeout_us=%ld"
|
|
|
|
The first parameter gives the QoS class name (e.g. "CPU_DMA_LATENCY").
|
|
The second parameter is value to be added/updated/removed.
|
|
The third parameter is timeout value in usec.
|
|
|
|
pm_qos_update_target "action=%s prev_value=%d curr_value=%d"
|
|
pm_qos_update_flags "action=%s prev_value=0x%x curr_value=0x%x"
|
|
|
|
The first parameter gives the QoS action name (e.g. "ADD_REQ").
|
|
The second parameter is the previous QoS value.
|
|
The third parameter is the current QoS value to update.
|
|
|
|
And, there are also events used for device PM QoS add/update/remove request.
|
|
|
|
dev_pm_qos_add_request "device=%s type=%s new_value=%d"
|
|
dev_pm_qos_update_request "device=%s type=%s new_value=%d"
|
|
dev_pm_qos_remove_request "device=%s type=%s new_value=%d"
|
|
|
|
The first parameter gives the device name which tries to add/update/remove
|
|
QoS requests.
|
|
The second parameter gives the request type (e.g. "DEV_PM_QOS_RESUME_LATENCY").
|
|
The third parameter is value to be added/updated/removed.
|