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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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4
arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
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@@ -33,6 +33,7 @@
#include <linux/cpufreq.h>
#include <linux/compiler.h>
#include <linux/dmi.h>
#include <linux/ftrace.h>
#include <linux/acpi.h>
#include <acpi/processor.h>
@@ -391,6 +392,7 @@ static int acpi_cpufreq_target(struct cpufreq_policy *policy,
unsigned int next_perf_state = 0; /* Index into perf table */
unsigned int i;
int result = 0;
struct power_trace it;
dprintk("acpi_cpufreq_target %d (%d)\n", target_freq, policy->cpu);
@@ -427,6 +429,8 @@ static int acpi_cpufreq_target(struct cpufreq_policy *policy,
}
}
trace_power_mark(&it, POWER_PSTATE, next_perf_state);
switch (data->cpu_feature) {
case SYSTEM_INTEL_MSR_CAPABLE:
cmd.type = SYSTEM_INTEL_MSR_CAPABLE;