Commit 47e073d2 authored by Changbin Du's avatar Changbin Du Committed by Jonathan Corbet

trace doc: convert trace/events-power.txt to rst format

This converts the plain text documentation to reStructuredText format and
add it into Sphinx TOC tree. No essential content change.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarChangbin Du <changbin.du@intel.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 3cdd868e
Subsystem Trace Points: power
=============================
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
- Power state switch which reports events related to suspend (S-states),
cpuidle (C-states) and cpufreq (P-states)
- System clock related changes
- Power domains related changes and transitions
This document describes what each of the tracepoints is and why they
might be useful.
......@@ -22,14 +23,16 @@ Cf. include/trace/events/power.h for the events definitions.
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"
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"
machine_suspend "state=%lu"
Note: the value of '-1' or '4294967295' for state means an exit from the current state,
......@@ -45,10 +48,11 @@ correctly draw the states diagrams and to calculate accurate statistics etc.
================
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"
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
......@@ -57,8 +61,9 @@ 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"
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.
......@@ -67,28 +72,31 @@ The second parameter is the power domain target state.
================
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"
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"
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"
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.
......
......@@ -14,3 +14,4 @@ Linux Tracing Technologies
tracepoints
events
events-kmem
events-power
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