cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

governor.c (2815B)

      1/*
      2 * governor.c - governor support
      3 *
      4 * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
      5 *               Shaohua Li <shaohua.li@intel.com>
      6 *               Adam Belay <abelay@novell.com>
      7 *
      8 * This code is licenced under the GPL.
      9 */
     10
     11#include <linux/cpu.h>
     12#include <linux/cpuidle.h>
     13#include <linux/mutex.h>
     14#include <linux/module.h>
     15#include <linux/pm_qos.h>
     16
     17#include "cpuidle.h"
     18
     19char param_governor[CPUIDLE_NAME_LEN];
     20
     21LIST_HEAD(cpuidle_governors);
     22struct cpuidle_governor *cpuidle_curr_governor;
     23struct cpuidle_governor *cpuidle_prev_governor;
     24
     25/**
     26 * cpuidle_find_governor - finds a governor of the specified name
     27 * @str: the name
     28 *
     29 * Must be called with cpuidle_lock acquired.
     30 */
     31struct cpuidle_governor *cpuidle_find_governor(const char *str)
     32{
     33	struct cpuidle_governor *gov;
     34
     35	list_for_each_entry(gov, &cpuidle_governors, governor_list)
     36		if (!strncasecmp(str, gov->name, CPUIDLE_NAME_LEN))
     37			return gov;
     38
     39	return NULL;
     40}
     41
     42/**
     43 * cpuidle_switch_governor - changes the governor
     44 * @gov: the new target governor
     45 * Must be called with cpuidle_lock acquired.
     46 */
     47int cpuidle_switch_governor(struct cpuidle_governor *gov)
     48{
     49	struct cpuidle_device *dev;
     50
     51	if (!gov)
     52		return -EINVAL;
     53
     54	if (gov == cpuidle_curr_governor)
     55		return 0;
     56
     57	cpuidle_uninstall_idle_handler();
     58
     59	if (cpuidle_curr_governor) {
     60		list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
     61			cpuidle_disable_device(dev);
     62	}
     63
     64	cpuidle_curr_governor = gov;
     65
     66	if (gov) {
     67		list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
     68			cpuidle_enable_device(dev);
     69		cpuidle_install_idle_handler();
     70		printk(KERN_INFO "cpuidle: using governor %s\n", gov->name);
     71	}
     72
     73	return 0;
     74}
     75
     76/**
     77 * cpuidle_register_governor - registers a governor
     78 * @gov: the governor
     79 */
     80int cpuidle_register_governor(struct cpuidle_governor *gov)
     81{
     82	int ret = -EEXIST;
     83
     84	if (!gov || !gov->select)
     85		return -EINVAL;
     86
     87	if (cpuidle_disabled())
     88		return -ENODEV;
     89
     90	mutex_lock(&cpuidle_lock);
     91	if (cpuidle_find_governor(gov->name) == NULL) {
     92		ret = 0;
     93		list_add_tail(&gov->governor_list, &cpuidle_governors);
     94		if (!cpuidle_curr_governor ||
     95		    !strncasecmp(param_governor, gov->name, CPUIDLE_NAME_LEN) ||
     96		    (cpuidle_curr_governor->rating < gov->rating &&
     97		     strncasecmp(param_governor, cpuidle_curr_governor->name,
     98				 CPUIDLE_NAME_LEN)))
     99			cpuidle_switch_governor(gov);
    100	}
    101	mutex_unlock(&cpuidle_lock);
    102
    103	return ret;
    104}
    105
    106/**
    107 * cpuidle_governor_latency_req - Compute a latency constraint for CPU
    108 * @cpu: Target CPU
    109 */
    110s64 cpuidle_governor_latency_req(unsigned int cpu)
    111{
    112	struct device *device = get_cpu_device(cpu);
    113	int device_req = dev_pm_qos_raw_resume_latency(device);
    114	int global_req = cpu_latency_qos_limit();
    115
    116	if (device_req > global_req)
    117		device_req = global_req;
    118
    119	return (s64)device_req * NSEC_PER_USEC;
    120}