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r: 3534
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c: 9d54329
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v: v3
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Dmitry Torokhov committed Jun 1, 2005
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2 changes: 1 addition & 1 deletion [refs]
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---
refs/heads/master: a913829e90e2af7a6e98f5aadcc9fec4dcf1ef64
refs/heads/master: 9d5432979951c8761c2b4517007039b9bcc1c110
128 changes: 128 additions & 0 deletions trunk/Documentation/cpu-freq/cpufreq-stats.txt
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CPU frequency and voltage scaling statictics in the Linux(TM) kernel


L i n u x c p u f r e q - s t a t s d r i v e r

- information for users -


Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>

Contents
1. Introduction
2. Statistics Provided (with example)
3. Configuring cpufreq-stats


1. Introduction

cpufreq-stats is a driver that provices CPU frequency statistics for each CPU.
This statistics is provided in /sysfs as a bunch of read_only interfaces. This
interface (when configured) will appear in a seperate directory under cpufreq
in /sysfs (<sysfs root>/devices/system/cpu/cpuX/cpufreq/stats/) for each CPU.
Various statistics will form read_only files under this directory.

This driver is designed to be independent of any particular cpufreq_driver
that may be running on your CPU. So, it will work with any cpufreq_driver.


2. Statistics Provided (with example)

cpufreq stats provides following statistics (explained in detail below).
- time_in_state
- total_trans
- trans_table

All the statistics will be from the time the stats driver has been inserted
to the time when a read of a particular statistic is done. Obviously, stats
driver will not have any information about the the frequcny transitions before
the stats driver insertion.

--------------------------------------------------------------------------------
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # ls -l
total 0
drwxr-xr-x 2 root root 0 May 14 16:06 .
drwxr-xr-x 3 root root 0 May 14 15:58 ..
-r--r--r-- 1 root root 4096 May 14 16:06 time_in_state
-r--r--r-- 1 root root 4096 May 14 16:06 total_trans
-r--r--r-- 1 root root 4096 May 14 16:06 trans_table
--------------------------------------------------------------------------------

- time_in_state
This gives the amount of time spent in each of the frequencies supported by
this CPU. The cat output will have "<frequency> <time>" pair in each line, which
will mean this CPU spent <time> usertime units of time at <frequency>. Output
will have one line for each of the supported freuencies. usertime units here
is 10mS (similar to other time exported in /proc).

--------------------------------------------------------------------------------
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat time_in_state
3600000 2089
3400000 136
3200000 34
3000000 67
2800000 172488
--------------------------------------------------------------------------------


- total_trans
This gives the total number of frequency transitions on this CPU. The cat
output will have a single count which is the total number of frequency
transitions.

--------------------------------------------------------------------------------
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat total_trans
20
--------------------------------------------------------------------------------

- trans_table
This will give a fine grained information about all the CPU frequency
transitions. The cat output here is a two dimensional matrix, where an entry
<i,j> (row i, column j) represents the count of number of transitions from
Freq_i to Freq_j. Freq_i is in descending order with increasing rows and
Freq_j is in descending order with increasing columns. The output here also
contains the actual freq values for each row and column for better readability.

--------------------------------------------------------------------------------
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat trans_table
From : To
: 3600000 3400000 3200000 3000000 2800000
3600000: 0 5 0 0 0
3400000: 4 0 2 0 0
3200000: 0 1 0 2 0
3000000: 0 0 1 0 3
2800000: 0 0 0 2 0
--------------------------------------------------------------------------------


3. Configuring cpufreq-stats

To configure cpufreq-stats in your kernel
Config Main Menu
Power management options (ACPI, APM) --->
CPU Frequency scaling --->
[*] CPU Frequency scaling
<*> CPU frequency translation statistics
[*] CPU frequency translation statistics details


"CPU Frequency scaling" (CONFIG_CPU_FREQ) should be enabled to configure
cpufreq-stats.

"CPU frequency translation statistics" (CONFIG_CPU_FREQ_STAT) provides the
basic statistics which includes time_in_state and total_trans.

"CPU frequency translation statistics details" (CONFIG_CPU_FREQ_STAT_DETAILS)
provides fine grained cpufreq stats by trans_table. The reason for having a
seperate config option for trans_table is:
- trans_table goes against the traditional /sysfs rule of one value per
interface. It provides a whole bunch of value in a 2 dimensional matrix
form.

Once these two options are enabled and your CPU supports cpufrequency, you
will be able to see the CPU frequency statistics in /sysfs.




4 changes: 2 additions & 2 deletions trunk/MAINTAINERS
Original file line number Diff line number Diff line change
Expand Up @@ -1023,8 +1023,8 @@ W: http://www.ia64-linux.org/
S: Maintained

SN-IA64 (Itanium) SUB-PLATFORM
P: Jesse Barnes
M: jbarnes@sgi.com
P: Greg Edwards
M: edwardsg@sgi.com
L: linux-altix@sgi.com
L: linux-ia64@vger.kernel.org
W: http://www.sgi.com/altix
Expand Down
2 changes: 1 addition & 1 deletion trunk/arch/h8300/kernel/process.c
Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,7 @@ asmlinkage void ret_from_fork(void);
void default_idle(void)
{
while(1) {
if (need_resched()) {
if (!need_resched()) {
local_irq_enable();
__asm__("sleep");
local_irq_disable();
Expand Down
14 changes: 13 additions & 1 deletion trunk/arch/i386/kernel/cpu/cpufreq/Kconfig
Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@ config X86_ACPI_CPUFREQ
If in doubt, say N.

config ELAN_CPUFREQ
tristate "AMD Elan"
tristate "AMD Elan SC400 and SC410"
select CPU_FREQ_TABLE
depends on X86_ELAN
---help---
Expand All @@ -38,6 +38,18 @@ config ELAN_CPUFREQ

If in doubt, say N.

config SC520_CPUFREQ
tristate "AMD Elan SC520"
select CPU_FREQ_TABLE
depends on X86_ELAN
---help---
This adds the CPUFreq driver for AMD Elan SC520 processor.

For details, take a look at <file:Documentation/cpu-freq/>.

If in doubt, say N.


config X86_POWERNOW_K6
tristate "AMD Mobile K6-2/K6-3 PowerNow!"
select CPU_FREQ_TABLE
Expand Down
1 change: 1 addition & 0 deletions trunk/arch/i386/kernel/cpu/cpufreq/Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ obj-$(CONFIG_X86_POWERNOW_K7) += powernow-k7.o
obj-$(CONFIG_X86_POWERNOW_K8) += powernow-k8.o
obj-$(CONFIG_X86_LONGHAUL) += longhaul.o
obj-$(CONFIG_ELAN_CPUFREQ) += elanfreq.o
obj-$(CONFIG_SC520_CPUFREQ) += sc520_freq.o
obj-$(CONFIG_X86_LONGRUN) += longrun.o
obj-$(CONFIG_X86_GX_SUSPMOD) += gx-suspmod.o
obj-$(CONFIG_X86_SPEEDSTEP_ICH) += speedstep-ich.o
Expand Down
58 changes: 53 additions & 5 deletions trunk/arch/i386/kernel/cpu/cpufreq/longhaul.c
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
#include <linux/cpufreq.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/pci.h>

#include <asm/msr.h>
#include <asm/timex.h>
Expand Down Expand Up @@ -119,7 +120,13 @@ static int longhaul_get_cpu_mult(void)
static void do_powersaver(union msr_longhaul *longhaul,
unsigned int clock_ratio_index)
{
struct pci_dev *dev;
unsigned long flags;
unsigned int tmp_mask;
int version;
int i;
u16 pci_cmd;
u16 cmd_state[64];

switch (cpu_model) {
case CPU_EZRA_T:
Expand All @@ -137,17 +144,58 @@ static void do_powersaver(union msr_longhaul *longhaul,
longhaul->bits.SoftBusRatio4 = (clock_ratio_index & 0x10) >> 4;
longhaul->bits.EnableSoftBusRatio = 1;
longhaul->bits.RevisionKey = 0;
local_irq_disable();
wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);

preempt_disable();
local_irq_save(flags);

/*
* get current pci bus master state for all devices
* and clear bus master bit
*/
dev = NULL;
i = 0;
do {
dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
if (dev != NULL) {
pci_read_config_word(dev, PCI_COMMAND, &pci_cmd);
cmd_state[i++] = pci_cmd;
pci_cmd &= ~PCI_COMMAND_MASTER;
pci_write_config_word(dev, PCI_COMMAND, pci_cmd);
}
} while (dev != NULL);

tmp_mask=inb(0x21); /* works on C3. save mask. */
outb(0xFE,0x21); /* TMR0 only */
outb(0xFF,0x80); /* delay */

local_irq_enable();

__hlt();
wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);
__hlt();

local_irq_disable();

outb(tmp_mask,0x21); /* restore mask */

/* restore pci bus master state for all devices */
dev = NULL;
i = 0;
do {
dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
if (dev != NULL) {
pci_cmd = cmd_state[i++];
pci_write_config_byte(dev, PCI_COMMAND, pci_cmd);
}
} while (dev != NULL);
local_irq_restore(flags);
preempt_enable();

/* disable bus ratio bit */
rdmsrl(MSR_VIA_LONGHAUL, longhaul->val);
longhaul->bits.EnableSoftBusRatio = 0;
longhaul->bits.RevisionKey = version;
local_irq_disable();
wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);
local_irq_enable();
}

/**
Expand Down Expand Up @@ -578,7 +626,7 @@ static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
longhaul_setup_voltagescaling();

policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
policy->cpuinfo.transition_latency = 200000; /* nsec */
policy->cur = calc_speed(longhaul_get_cpu_mult());

ret = cpufreq_frequency_table_cpuinfo(policy, longhaul_table);
Expand Down
11 changes: 8 additions & 3 deletions trunk/arch/i386/kernel/cpu/cpufreq/powernow-k7.c
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
#include <linux/dmi.h>

#include <asm/msr.h>
#include <asm/timer.h>
#include <asm/timex.h>
#include <asm/io.h>
#include <asm/system.h>
Expand Down Expand Up @@ -586,13 +587,17 @@ static int __init powernow_cpu_init (struct cpufreq_policy *policy)

rdmsrl (MSR_K7_FID_VID_STATUS, fidvidstatus.val);

/* A K7 with powernow technology is set to max frequency by BIOS */
fsb = (10 * cpu_khz) / fid_codes[fidvidstatus.bits.MFID];
/* recalibrate cpu_khz */
result = recalibrate_cpu_khz();
if (result)
return result;

fsb = (10 * cpu_khz) / fid_codes[fidvidstatus.bits.CFID];
if (!fsb) {
printk(KERN_WARNING PFX "can not determine bus frequency\n");
return -EINVAL;
}
dprintk("FSB: %3d.%03d MHz\n", fsb/1000, fsb%1000);
dprintk("FSB: %3dMHz\n", fsb/1000);

if (dmi_check_system(powernow_dmi_table) || acpi_force) {
printk (KERN_INFO PFX "PSB/PST known to be broken. Trying ACPI instead\n");
Expand Down
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