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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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16
arch/x86/kernel/process.c
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@@ -7,6 +7,7 @@
#include <linux/module.h>
#include <linux/pm.h>
#include <linux/clockchips.h>
#include <linux/ftrace.h>
#include <asm/system.h>
unsigned long idle_halt;
@@ -100,6 +101,9 @@ static inline int hlt_use_halt(void)
void default_idle(void)
{
if (hlt_use_halt()) {
struct power_trace it;
trace_power_start(&it, POWER_CSTATE, 1);
current_thread_info()->status &= ~TS_POLLING;
/*
* TS_POLLING-cleared state must be visible before we
@@ -112,6 +116,7 @@ void default_idle(void)
else
local_irq_enable();
current_thread_info()->status |= TS_POLLING;
trace_power_end(&it);
} else {
local_irq_enable();
/* loop is done by the caller */
@@ -154,24 +159,31 @@ EXPORT_SYMBOL_GPL(cpu_idle_wait);
*/
void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
{
struct power_trace it;
trace_power_start(&it, POWER_CSTATE, (ax>>4)+1);
if (!need_resched()) {
__monitor((void *)&current_thread_info()->flags, 0, 0);
smp_mb();
if (!need_resched())
__mwait(ax, cx);
}
trace_power_end(&it);
}
/* Default MONITOR/MWAIT with no hints, used for default C1 state */
static void mwait_idle(void)
{
struct power_trace it;
if (!need_resched()) {
trace_power_start(&it, POWER_CSTATE, 1);
__monitor((void *)&current_thread_info()->flags, 0, 0);
smp_mb();
if (!need_resched())
__sti_mwait(0, 0);
else
local_irq_enable();
trace_power_end(&it);
} else
local_irq_enable();
}
@@ -183,9 +195,13 @@ static void mwait_idle(void)
*/
static void poll_idle(void)
{
struct power_trace it;
trace_power_start(&it, POWER_CSTATE, 0);
local_irq_enable();
while (!need_resched())
cpu_relax();
trace_power_end(&it);
}
/*