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Message-ID: <tip-4b95f135f606c87e4056b6d7fd3c5781c818858b@git.kernel.org> Date: Wed, 5 Jan 2011 21:25:06 GMT From: tip-bot for Jean Pihet <j-pihet@...com> To: linux-tip-commits@...r.kernel.org Cc: linux-kernel@...r.kernel.org, acme@...hat.com, hpa@...or.com, mingo@...hat.com, arjan@...ux.intel.com, j-pihet@...com, pavel@....cz, rostedt@...dmis.org, tglx@...utronix.de, rjw@...k.pl, mingo@...e.hu, len.brown@...el.com Subject: [tip:perf/core] tools, perf: Documentation for the power events API Commit-ID: 4b95f135f606c87e4056b6d7fd3c5781c818858b Gitweb: http://git.kernel.org/tip/4b95f135f606c87e4056b6d7fd3c5781c818858b Author: Jean Pihet <j-pihet@...com> AuthorDate: Wed, 5 Jan 2011 19:49:02 +0100 Committer: Ingo Molnar <mingo@...e.hu> CommitDate: Wed, 5 Jan 2011 21:25:29 +0100 tools, perf: Documentation for the power events API Provides documentation for the following: - the new power trace API, - the old (legacy) power trace API, - the DEPRECATED Kconfig option usage. Signed-off-by: Jean Pihet <j-pihet@...com> Cc: Arjan van de Ven <arjan@...ux.intel.com> Cc: trenn@...e.de Cc: Len Brown <len.brown@...el.com> Cc: Pavel Machek <pavel@....cz> Cc: Rafael J. Wysocki <rjw@...k.pl> Cc: Steven Rostedt <rostedt@...dmis.org> Cc: Arnaldo Carvalho de Melo <acme@...hat.com> Cc: linux-pm@...ts.linux-foundation.org LKML-Reference: <1294253342-29056-3-git-send-email-j-pihet@...com> Signed-off-by: Ingo Molnar <mingo@...e.hu> --- Documentation/trace/events-power.txt | 90 ++++++++++++++++++++++++++++++++++ 1 files changed, 90 insertions(+), 0 deletions(-) diff --git a/Documentation/trace/events-power.txt b/Documentation/trace/events-power.txt new file mode 100644 index 0000000..96d87b6 --- /dev/null +++ b/Documentation/trace/events-power.txt @@ -0,0 +1,90 @@ + + 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 New 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. + +1.2 DEPRECATED trace API +------------------------ + +A new Kconfig option CONFIG_EVENT_POWER_TRACING_DEPRECATED with the default value of +'y' has been created. This allows the legacy trace power API to be used conjointly +with the new trace API. +The Kconfig option, the old trace API (in include/trace/events/power.h) and the +old trace points will disappear in a future release (namely 2.6.41). + +power_start "type=%lu state=%lu cpu_id=%lu" +power_frequency "type=%lu state=%lu cpu_id=%lu" +power_end "cpu_id=%lu" + +The 'type' parameter takes one of those macros: + . POWER_NONE = 0, + . POWER_CSTATE = 1, /* C-State */ + . POWER_PSTATE = 2, /* Fequency change or DVFS */ + +The 'state' parameter is set depending on the type: + . Target C-state for type=POWER_CSTATE, + . Target frequency for type=POWER_PSTATE, + +power_end is used to indicate the exit of a state, corresponding to the latest +power_start event. + +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. + -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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