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linux-2.6/include/linux/cpufreq.h
Venkatesh Pallipadi dfde5d62ed [CPUFREQ][8/8] acpi-cpufreq: Add support for freq feedback from hardware 
Enable ondemand governor and acpi-cpufreq to use IA32_APERF and IA32_MPERF MSR
to get active frequency feedback for the last sampling interval. This will
make ondemand take right frequency decisions when hardware coordination of
frequency is going on.

Without APERF/MPERF, ondemand can take wrong decision at times due
to underlying hardware coordination or TM2.
Example:
* CPU 0 and CPU 1 are hardware cooridnated.
* CPU 1 running at highest frequency.
* CPU 0 was running at highest freq. Now ondemand reduces it to
  some intermediate frequency based on utilization.
* Due to underlying hardware coordination with other CPU 1, CPU 0 continues to
  run at highest frequency (as long as other CPU is at highest).
* When ondemand samples CPU 0 again next time, without actual frequency
  feedback from APERF/MPERF, it will think that previous frequency change
  was successful and can go to wrong target frequency. This is because it
  thinks that utilization it has got this sampling interval is when running at
  intermediate frequency, rather than actual highest frequency.

More information about IA32_APERF IA32_MPERF MSR:
Refer to IA-32 Intel® Architecture Software Developer's Manual at
http://developer.intel.com

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-10-15 19:57:11 -04:00

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/*
* linux/include/linux/cpufreq.h
*
* Copyright (C) 2001 Russell King
* (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
*
*
* $Id: cpufreq.h,v 1.36 2003/01/20 17:31:48 db Exp $
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _LINUX_CPUFREQ_H
#define _LINUX_CPUFREQ_H
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/threads.h>
#include <linux/device.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <linux/completion.h>
#include <linux/workqueue.h>
#include <linux/cpumask.h>
#include <asm/div64.h>
#define CPUFREQ_NAME_LEN 16
/*********************************************************************
* CPUFREQ NOTIFIER INTERFACE *
*********************************************************************/
int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list);
int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list);
#define CPUFREQ_TRANSITION_NOTIFIER (0)
#define CPUFREQ_POLICY_NOTIFIER (1)
/* if (cpufreq_driver->target) exists, the ->governor decides what frequency
* within the limits is used. If (cpufreq_driver->setpolicy> exists, these
* two generic policies are available:
*/
#define CPUFREQ_POLICY_POWERSAVE (1)
#define CPUFREQ_POLICY_PERFORMANCE (2)
/* Frequency values here are CPU kHz so that hardware which doesn't run
* with some frequencies can complain without having to guess what per
* cent / per mille means.
* Maximum transition latency is in nanoseconds - if it's unknown,
* CPUFREQ_ETERNAL shall be used.
*/
struct cpufreq_governor;
#define CPUFREQ_ETERNAL (-1)
struct cpufreq_cpuinfo {
unsigned int max_freq;
unsigned int min_freq;
unsigned int transition_latency; /* in 10^(-9) s = nanoseconds */
};
struct cpufreq_real_policy {
unsigned int min; /* in kHz */
unsigned int max; /* in kHz */
unsigned int policy; /* see above */
struct cpufreq_governor *governor; /* see below */
};
struct cpufreq_policy {
cpumask_t cpus; /* affected CPUs */
unsigned int shared_type; /* ANY or ALL affected CPUs
should set cpufreq */
unsigned int cpu; /* cpu nr of registered CPU */
struct cpufreq_cpuinfo cpuinfo;/* see above */
unsigned int min; /* in kHz */
unsigned int max; /* in kHz */
unsigned int cur; /* in kHz, only needed if cpufreq
* governors are used */
unsigned int policy; /* see above */
struct cpufreq_governor *governor; /* see below */
struct mutex lock; /* CPU ->setpolicy or ->target may
only be called once a time */
struct work_struct update; /* if update_policy() needs to be
* called, but you're in IRQ context */
struct cpufreq_real_policy user_policy;
struct kobject kobj;
struct completion kobj_unregister;
};
#define CPUFREQ_ADJUST (0)
#define CPUFREQ_INCOMPATIBLE (1)
#define CPUFREQ_NOTIFY (2)
#define CPUFREQ_SHARED_TYPE_NONE (0) /* None */
#define CPUFREQ_SHARED_TYPE_HW (1) /* HW does needed coordination */
#define CPUFREQ_SHARED_TYPE_ALL (2) /* All dependent CPUs should set freq */
#define CPUFREQ_SHARED_TYPE_ANY (3) /* Freq can be set from any dependent CPU*/
/******************** cpufreq transition notifiers *******************/
#define CPUFREQ_PRECHANGE (0)
#define CPUFREQ_POSTCHANGE (1)
#define CPUFREQ_RESUMECHANGE (8)
#define CPUFREQ_SUSPENDCHANGE (9)
struct cpufreq_freqs {
unsigned int cpu; /* cpu nr */
unsigned int old;
unsigned int new;
u8 flags; /* flags of cpufreq_driver, see below. */
};
/**
* cpufreq_scale - "old * mult / div" calculation for large values (32-bit-arch safe)
* @old: old value
* @div: divisor
* @mult: multiplier
*
*
* new = old * mult / div
*/
static inline unsigned long cpufreq_scale(unsigned long old, u_int div, u_int mult)
{
#if BITS_PER_LONG == 32
u64 result = ((u64) old) * ((u64) mult);
do_div(result, div);
return (unsigned long) result;
#elif BITS_PER_LONG == 64
unsigned long result = old * ((u64) mult);
result /= div;
return result;
#endif
};
/*********************************************************************
* CPUFREQ GOVERNORS *
*********************************************************************/
#define CPUFREQ_GOV_START 1
#define CPUFREQ_GOV_STOP 2
#define CPUFREQ_GOV_LIMITS 3
struct cpufreq_governor {
char name[CPUFREQ_NAME_LEN];
int (*governor) (struct cpufreq_policy *policy,
unsigned int event);
struct list_head governor_list;
struct module *owner;
};
/* pass a target to the cpufreq driver
*/
extern int cpufreq_driver_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation);
extern int __cpufreq_driver_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation);
extern int cpufreq_driver_getavg(struct cpufreq_policy *policy);
int cpufreq_register_governor(struct cpufreq_governor *governor);
void cpufreq_unregister_governor(struct cpufreq_governor *governor);
/*********************************************************************
* CPUFREQ DRIVER INTERFACE *
*********************************************************************/
#define CPUFREQ_RELATION_L 0 /* lowest frequency at or above target */
#define CPUFREQ_RELATION_H 1 /* highest frequency below or at target */
struct freq_attr;
struct cpufreq_driver {
struct module *owner;
char name[CPUFREQ_NAME_LEN];
u8 flags;
/* needed by all drivers */
int (*init) (struct cpufreq_policy *policy);
int (*verify) (struct cpufreq_policy *policy);
/* define one out of two */
int (*setpolicy) (struct cpufreq_policy *policy);
int (*target) (struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation);
/* should be defined, if possible */
unsigned int (*get) (unsigned int cpu);
/* optional */
unsigned int (*getavg) (unsigned int cpu);
int (*exit) (struct cpufreq_policy *policy);
int (*suspend) (struct cpufreq_policy *policy, pm_message_t pmsg);
int (*resume) (struct cpufreq_policy *policy);
struct freq_attr **attr;
};
/* flags */
#define CPUFREQ_STICKY 0x01 /* the driver isn't removed even if
* all ->init() calls failed */
#define CPUFREQ_CONST_LOOPS 0x02 /* loops_per_jiffy or other kernel
* "constants" aren't affected by
* frequency transitions */
#define CPUFREQ_PM_NO_WARN 0x04 /* don't warn on suspend/resume speed
* mismatches */
int cpufreq_register_driver(struct cpufreq_driver *driver_data);
int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state);
static inline void cpufreq_verify_within_limits(struct cpufreq_policy *policy, unsigned int min, unsigned int max)
{
if (policy->min < min)
policy->min = min;
if (policy->max < min)
policy->max = min;
if (policy->min > max)
policy->min = max;
if (policy->max > max)
policy->max = max;
if (policy->min > policy->max)
policy->min = policy->max;
return;
}
struct freq_attr {
struct attribute attr;
ssize_t (*show)(struct cpufreq_policy *, char *);
ssize_t (*store)(struct cpufreq_policy *, const char *, size_t count);
};
/*********************************************************************
* CPUFREQ 2.6. INTERFACE *
*********************************************************************/
int cpufreq_set_policy(struct cpufreq_policy *policy);
int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu);
int cpufreq_update_policy(unsigned int cpu);
/* query the current CPU frequency (in kHz). If zero, cpufreq couldn't detect it */
unsigned int cpufreq_get(unsigned int cpu);
/* query the last known CPU freq (in kHz). If zero, cpufreq couldn't detect it */
#ifdef CONFIG_CPU_FREQ
unsigned int cpufreq_quick_get(unsigned int cpu);
#else
static inline unsigned int cpufreq_quick_get(unsigned int cpu)
{
return 0;
}
#endif
/*********************************************************************
* CPUFREQ DEFAULT GOVERNOR *
*********************************************************************/
#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE
extern struct cpufreq_governor cpufreq_gov_performance;
#define CPUFREQ_DEFAULT_GOVERNOR &cpufreq_gov_performance
#elif defined(CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE)
extern struct cpufreq_governor cpufreq_gov_userspace;
#define CPUFREQ_DEFAULT_GOVERNOR &cpufreq_gov_userspace
#endif
/*********************************************************************
* FREQUENCY TABLE HELPERS *
*********************************************************************/
#define CPUFREQ_ENTRY_INVALID ~0
#define CPUFREQ_TABLE_END ~1
struct cpufreq_frequency_table {
unsigned int index; /* any */
unsigned int frequency; /* kHz - doesn't need to be in ascending
* order */
};
int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
struct cpufreq_frequency_table *table);
int cpufreq_frequency_table_verify(struct cpufreq_policy *policy,
struct cpufreq_frequency_table *table);
int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
struct cpufreq_frequency_table *table,
unsigned int target_freq,
unsigned int relation,
unsigned int *index);
/* the following 3 funtions are for cpufreq core use only */
struct cpufreq_frequency_table *cpufreq_frequency_get_table(unsigned int cpu);
struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu);
void cpufreq_cpu_put (struct cpufreq_policy *data);
/* the following are really really optional */
extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs;
void cpufreq_frequency_table_get_attr(struct cpufreq_frequency_table *table,
unsigned int cpu);
void cpufreq_frequency_table_put_attr(unsigned int cpu);
/*********************************************************************
* UNIFIED DEBUG HELPERS *
*********************************************************************/
#define CPUFREQ_DEBUG_CORE 1
#define CPUFREQ_DEBUG_DRIVER 2
#define CPUFREQ_DEBUG_GOVERNOR 4
#ifdef CONFIG_CPU_FREQ_DEBUG
extern void cpufreq_debug_printk(unsigned int type, const char *prefix,
const char *fmt, ...);
#else
#define cpufreq_debug_printk(msg...) do { } while(0)
#endif /* CONFIG_CPU_FREQ_DEBUG */
#endif /* _LINUX_CPUFREQ_H */
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