e788892ba3
The design of the cpufreq governor API is not very straightforward, as struct cpufreq_governor provides only one callback to be invoked from different code paths for different purposes. The purpose it is invoked for is determined by its second "event" argument, causing it to act as a "callback multiplexer" of sorts. Unfortunately, that leads to extra complexity in governors, some of which implement the ->governor() callback as a switch statement that simply checks the event argument and invokes a separate function to handle that specific event. That extra complexity can be eliminated by replacing the all-purpose ->governor() callback with a family of callbacks to carry out specific governor operations: initialization and exit, start and stop and policy limits updates. That also turns out to reduce the code size too, so do it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
168 lines
4.1 KiB
C
168 lines
4.1 KiB
C
/*
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* spu aware cpufreq governor for the cell processor
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*
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* © Copyright IBM Corporation 2006-2008
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*
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* Author: Christian Krafft <krafft@de.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/cpufreq.h>
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#include <linux/sched.h>
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#include <linux/module.h>
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#include <linux/timer.h>
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#include <linux/workqueue.h>
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#include <linux/atomic.h>
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#include <asm/machdep.h>
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#include <asm/spu.h>
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#define POLL_TIME 100000 /* in µs */
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#define EXP 753 /* exp(-1) in fixed-point */
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struct spu_gov_info_struct {
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unsigned long busy_spus; /* fixed-point */
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struct cpufreq_policy *policy;
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struct delayed_work work;
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unsigned int poll_int; /* µs */
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};
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static DEFINE_PER_CPU(struct spu_gov_info_struct, spu_gov_info);
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static int calc_freq(struct spu_gov_info_struct *info)
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{
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int cpu;
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int busy_spus;
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cpu = info->policy->cpu;
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busy_spus = atomic_read(&cbe_spu_info[cpu_to_node(cpu)].busy_spus);
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CALC_LOAD(info->busy_spus, EXP, busy_spus * FIXED_1);
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pr_debug("cpu %d: busy_spus=%d, info->busy_spus=%ld\n",
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cpu, busy_spus, info->busy_spus);
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return info->policy->max * info->busy_spus / FIXED_1;
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}
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static void spu_gov_work(struct work_struct *work)
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{
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struct spu_gov_info_struct *info;
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int delay;
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unsigned long target_freq;
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info = container_of(work, struct spu_gov_info_struct, work.work);
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/* after cancel_delayed_work_sync we unset info->policy */
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BUG_ON(info->policy == NULL);
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target_freq = calc_freq(info);
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__cpufreq_driver_target(info->policy, target_freq, CPUFREQ_RELATION_H);
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delay = usecs_to_jiffies(info->poll_int);
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schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
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}
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static void spu_gov_init_work(struct spu_gov_info_struct *info)
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{
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int delay = usecs_to_jiffies(info->poll_int);
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INIT_DEFERRABLE_WORK(&info->work, spu_gov_work);
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schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
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}
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static void spu_gov_cancel_work(struct spu_gov_info_struct *info)
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{
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cancel_delayed_work_sync(&info->work);
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}
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static int spu_gov_start(struct cpufreq_policy *policy)
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{
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unsigned int cpu = policy->cpu;
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struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
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struct spu_gov_info_struct *affected_info;
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int i;
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if (!cpu_online(cpu)) {
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printk(KERN_ERR "cpu %d is not online\n", cpu);
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return -EINVAL;
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}
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if (!policy->cur) {
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printk(KERN_ERR "no cpu specified in policy\n");
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return -EINVAL;
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}
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/* initialize spu_gov_info for all affected cpus */
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for_each_cpu(i, policy->cpus) {
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affected_info = &per_cpu(spu_gov_info, i);
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affected_info->policy = policy;
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}
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info->poll_int = POLL_TIME;
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/* setup timer */
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spu_gov_init_work(info);
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return 0;
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}
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static void spu_gov_stop(struct cpufreq_policy *policy)
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{
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unsigned int cpu = policy->cpu;
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struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
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int i;
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/* cancel timer */
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spu_gov_cancel_work(info);
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/* clean spu_gov_info for all affected cpus */
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for_each_cpu (i, policy->cpus) {
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info = &per_cpu(spu_gov_info, i);
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info->policy = NULL;
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}
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}
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static struct cpufreq_governor spu_governor = {
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.name = "spudemand",
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.start = spu_gov_start,
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.stop = spu_gov_stop,
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.owner = THIS_MODULE,
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};
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/*
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* module init and destoy
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*/
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static int __init spu_gov_init(void)
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{
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int ret;
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ret = cpufreq_register_governor(&spu_governor);
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if (ret)
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printk(KERN_ERR "registration of governor failed\n");
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return ret;
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}
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static void __exit spu_gov_exit(void)
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{
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cpufreq_unregister_governor(&spu_governor);
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}
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module_init(spu_gov_init);
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module_exit(spu_gov_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
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