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

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

View File

@ -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;

View File

@ -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);
}
/*

View File

@ -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.

View File

@ -217,6 +217,17 @@ config BRANCH_TRACER
Say N if unsure.
config POWER_TRACER
bool "Trace power consumption behavior"
depends on DEBUG_KERNEL
depends on X86
select TRACING
help
This tracer helps developers to analyze and optimize the kernels
power management decisions, specifically the C-state and P-state
behavior.
config STACK_TRACER
bool "Trace max stack"
depends on HAVE_FUNCTION_TRACER

View File

@ -32,5 +32,6 @@ obj-$(CONFIG_BOOT_TRACER) += trace_boot.o
obj-$(CONFIG_FUNCTION_RET_TRACER) += trace_functions_return.o
obj-$(CONFIG_TRACE_BRANCH_PROFILING) += trace_branch.o
obj-$(CONFIG_BTS_TRACER) += trace_bts.o
obj-$(CONFIG_POWER_TRACER) += trace_power.o
libftrace-y := ftrace.o

View File

@ -28,6 +28,7 @@ enum trace_type {
TRACE_FN_RET,
TRACE_USER_STACK,
TRACE_BTS,
TRACE_POWER,
__TRACE_LAST_TYPE
};
@ -160,6 +161,11 @@ struct bts_entry {
unsigned long to;
};
struct trace_power {
struct trace_entry ent;
struct power_trace state_data;
};
/*
* trace_flag_type is an enumeration that holds different
* states when a trace occurs. These are:
@ -266,6 +272,7 @@ extern void __ftrace_bad_type(void);
IF_ASSIGN(var, ent, struct trace_branch, TRACE_BRANCH); \
IF_ASSIGN(var, ent, struct ftrace_ret_entry, TRACE_FN_RET);\
IF_ASSIGN(var, ent, struct bts_entry, TRACE_BTS);\
IF_ASSIGN(var, ent, struct trace_power, TRACE_POWER); \
__ftrace_bad_type(); \
} while (0)

179
kernel/trace/trace_power.c Normal file
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@ -0,0 +1,179 @@
/*
* ring buffer based C-state tracer
*
* Arjan van de Ven <arjan@linux.intel.com>
* Copyright (C) 2008 Intel Corporation
*
* Much is borrowed from trace_boot.c which is
* Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
*
*/
#include <linux/init.h>
#include <linux/debugfs.h>
#include <linux/ftrace.h>
#include <linux/kallsyms.h>
#include <linux/module.h>
#include "trace.h"
static struct trace_array *power_trace;
static int __read_mostly trace_power_enabled;
static void start_power_trace(struct trace_array *tr)
{
trace_power_enabled = 1;
}
static void stop_power_trace(struct trace_array *tr)
{
trace_power_enabled = 0;
}
static int power_trace_init(struct trace_array *tr)
{
int cpu;
power_trace = tr;
trace_power_enabled = 1;
for_each_cpu_mask(cpu, cpu_possible_map)
tracing_reset(tr, cpu);
return 0;
}
static enum print_line_t power_print_line(struct trace_iterator *iter)
{
int ret = 0;
struct trace_entry *entry = iter->ent;
struct trace_power *field ;
struct power_trace *it;
struct trace_seq *s = &iter->seq;
struct timespec stamp;
struct timespec duration;
trace_assign_type(field, entry);
it = &field->state_data;
stamp = ktime_to_timespec(it->stamp);
duration = ktime_to_timespec(ktime_sub(it->end, it->stamp));
if (entry->type == TRACE_POWER) {
if (it->type == POWER_CSTATE)
ret = trace_seq_printf(s, "[%5ld.%09ld] CSTATE: Going to C%i on cpu %i for %ld.%09ld\n",
stamp.tv_sec,
stamp.tv_nsec,
it->state, iter->cpu,
duration.tv_sec,
duration.tv_nsec);
if (it->type == POWER_PSTATE)
ret = trace_seq_printf(s, "[%5ld.%09ld] PSTATE: Going to P%i on cpu %i\n",
stamp.tv_sec,
stamp.tv_nsec,
it->state, iter->cpu);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
return TRACE_TYPE_HANDLED;
}
return TRACE_TYPE_UNHANDLED;
}
static struct tracer power_tracer __read_mostly =
{
.name = "power",
.init = power_trace_init,
.start = start_power_trace,
.stop = stop_power_trace,
.reset = stop_power_trace,
.print_line = power_print_line,
};
static int init_power_trace(void)
{
return register_tracer(&power_tracer);
}
device_initcall(init_power_trace);
void trace_power_start(struct power_trace *it, unsigned int type,
unsigned int level)
{
if (!trace_power_enabled)
return;
memset(it, 0, sizeof(struct power_trace));
it->state = level;
it->type = type;
it->stamp = ktime_get();
}
EXPORT_SYMBOL_GPL(trace_power_start);
void trace_power_end(struct power_trace *it)
{
struct ring_buffer_event *event;
struct trace_power *entry;
struct trace_array_cpu *data;
unsigned long irq_flags;
struct trace_array *tr = power_trace;
if (!trace_power_enabled)
return;
preempt_disable();
it->end = ktime_get();
data = tr->data[smp_processor_id()];
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
goto out;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, 0, 0);
entry->ent.type = TRACE_POWER;
entry->state_data = *it;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
trace_wake_up();
out:
preempt_enable();
}
EXPORT_SYMBOL_GPL(trace_power_end);
void trace_power_mark(struct power_trace *it, unsigned int type,
unsigned int level)
{
struct ring_buffer_event *event;
struct trace_power *entry;
struct trace_array_cpu *data;
unsigned long irq_flags;
struct trace_array *tr = power_trace;
if (!trace_power_enabled)
return;
memset(it, 0, sizeof(struct power_trace));
it->state = level;
it->type = type;
it->stamp = ktime_get();
preempt_disable();
it->end = it->stamp;
data = tr->data[smp_processor_id()];
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
goto out;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, 0, 0);
entry->ent.type = TRACE_POWER;
entry->state_data = *it;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
trace_wake_up();
out:
preempt_enable();
}
EXPORT_SYMBOL_GPL(trace_power_mark);

108
scripts/trace/power.pl Normal file
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@ -0,0 +1,108 @@
#!/usr/bin/perl
# Copyright 2008, Intel Corporation
#
# This file is part of the Linux kernel
#
# This program file is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program in a file named COPYING; if not, write to the
# Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor,
# Boston, MA 02110-1301 USA
#
# Authors:
# Arjan van de Ven <arjan@linux.intel.com>
#
# This script turns a cstate ftrace output into a SVG graphic that shows
# historic C-state information
#
#
# cat /sys/kernel/debug/tracing/trace | perl power.pl > out.svg
#
my @styles;
my $base = 0;
my @pstate_last;
my @pstate_level;
$styles[0] = "fill:rgb(0,0,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
$styles[1] = "fill:rgb(0,255,0);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
$styles[2] = "fill:rgb(255,0,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
$styles[3] = "fill:rgb(255,255,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
$styles[4] = "fill:rgb(255,0,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
$styles[5] = "fill:rgb(0,255,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
$styles[6] = "fill:rgb(0,128,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
$styles[7] = "fill:rgb(0,255,128);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
$styles[8] = "fill:rgb(0,25,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
print "<?xml version=\"1.0\" standalone=\"no\"?> \n";
print "<svg width=\"10000\" height=\"100%\" version=\"1.1\" xmlns=\"http://www.w3.org/2000/svg\">\n";
my $scale = 30000.0;
while (<>) {
my $line = $_;
if ($line =~ /([0-9\.]+)\] CSTATE: Going to C([0-9]) on cpu ([0-9]+) for ([0-9\.]+)/) {
if ($base == 0) {
$base = $1;
}
my $time = $1 - $base;
$time = $time * $scale;
my $C = $2;
my $cpu = $3;
my $y = 400 * $cpu;
my $duration = $4 * $scale;
my $msec = int($4 * 100000)/100.0;
my $height = $C * 20;
$style = $styles[$C];
$y = $y + 140 - $height;
$x2 = $time + 4;
$y2 = $y + 4;
print "<rect x=\"$time\" width=\"$duration\" y=\"$y\" height=\"$height\" style=\"$style\"/>\n";
print "<text transform=\"translate($x2,$y2) rotate(90)\">C$C $msec</text>\n";
}
if ($line =~ /([0-9\.]+)\] PSTATE: Going to P([0-9]) on cpu ([0-9]+)/) {
my $time = $1 - $base;
my $state = $2;
my $cpu = $3;
if (defined($pstate_last[$cpu])) {
my $from = $pstate_last[$cpu];
my $oldstate = $pstate_state[$cpu];
my $duration = ($time-$from) * $scale;
$from = $from * $scale;
my $to = $from + $duration;
my $height = 140 - ($oldstate * (140/8));
my $y = 400 * $cpu + 200 + $height;
my $y2 = $y+4;
my $style = $styles[8];
print "<rect x=\"$from\" y=\"$y\" width=\"$duration\" height=\"5\" style=\"$style\"/>\n";
print "<text transform=\"translate($from,$y2)\">P$oldstate (cpu $cpu)</text>\n";
};
$pstate_last[$cpu] = $time;
$pstate_state[$cpu] = $state;
}
}
print "</svg>\n";