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tracing: add "power-tracer": C/P state tracer to help power optimization

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Impact: new "power-tracer" ftrace plugin

This patch adds a C/P-state ftrace plugin that will generate
detailed statistics about the C/P-states that are being used,
so that we can look at detailed decisions that the C/P-state
code is making, rather than the too high level "average"
that we have today.

An example way of using this is:

 mount -t debugfs none /sys/kernel/debug
 echo cstate > /sys/kernel/debug/tracing/current_tracer
 echo 1 > /sys/kernel/debug/tracing/tracing_enabled
 sleep 1
 echo 0 > /sys/kernel/debug/tracing/tracing_enabled
 cat /sys/kernel/debug/tracing/trace | perl scripts/trace/cstate.pl > out.svg

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arjan van de Ven 2008-11-23 16:49:58 -08:00 • committed by Ingo Molnar
parent 509dceef64
commit f3f47a6768
8 changed files with 355 additions and 0 deletions
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29
include/linux/ftrace.h
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@ -311,6 +311,35 @@ ftrace_init_module(struct module *mod,
unsigned long *start, unsigned long *end) { }
#endif
enum {
POWER_NONE = 0,
POWER_CSTATE = 1,
POWER_PSTATE = 2,
};
struct power_trace {
#ifdef CONFIG_POWER_TRACER
ktime_t stamp;
ktime_t end;
int type;
int state;
#endif
};
#ifdef CONFIG_POWER_TRACER
extern void trace_power_start(struct power_trace *it, unsigned int type,
unsigned int state);
extern void trace_power_mark(struct power_trace *it, unsigned int type,
unsigned int state);
extern void trace_power_end(struct power_trace *it);
#else
static inline void trace_power_start(struct power_trace *it, unsigned int type,
unsigned int state) { }
static inline void trace_power_mark(struct power_trace *it, unsigned int type,
unsigned int state) { }
static inline void trace_power_end(struct power_trace *it) { }
#endif
/*
* Structure that defines a return function trace.