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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/trace/events-power.txt
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
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+
+ 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.