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![Fabio Baltieri](/assets/img/avatar_default.png)
Fix cpufreq_gov_ondemand to skip CPU where another governor is used. The bug present itself as NULL pointer access on the mutex_lock() call, an can be reproduced on an SMP machine by setting the default governor to anything other than ondemand, setting a single CPU's governor to ondemand, then changing the sample rate by writing on: > /sys/devices/system/cpu/cpufreq/ondemand/sampling_rate Backtrace: Nov 26 17:36:54 balto kernel: [ 839.585241] BUG: unable to handle kernel NULL pointer dereference at (null) Nov 26 17:36:54 balto kernel: [ 839.585311] IP: [<ffffffff8174e082>] __mutex_lock_slowpath+0xb2/0x170 [snip] Nov 26 17:36:54 balto kernel: [ 839.587005] Call Trace: Nov 26 17:36:54 balto kernel: [ 839.587030] [<ffffffff8174da82>] mutex_lock+0x22/0x40 Nov 26 17:36:54 balto kernel: [ 839.587067] [<ffffffff81610b8f>] store_sampling_rate+0xbf/0x150 Nov 26 17:36:54 balto kernel: [ 839.587110] [<ffffffff81031e9c>] ? __do_page_fault+0x1cc/0x4c0 Nov 26 17:36:54 balto kernel: [ 839.587153] [<ffffffff813309bf>] kobj_attr_store+0xf/0x20 Nov 26 17:36:54 balto kernel: [ 839.587192] [<ffffffff811bb62d>] sysfs_write_file+0xcd/0x140 Nov 26 17:36:54 balto kernel: [ 839.587234] [<ffffffff8114c12c>] vfs_write+0xac/0x180 Nov 26 17:36:54 balto kernel: [ 839.587271] [<ffffffff8114c472>] sys_write+0x52/0xa0 Nov 26 17:36:54 balto kernel: [ 839.587306] [<ffffffff810321ce>] ? do_page_fault+0xe/0x10 Nov 26 17:36:54 balto kernel: [ 839.587345] [<ffffffff81751202>] system_call_fastpath+0x16/0x1b Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
542 lines
15 KiB
C
542 lines
15 KiB
C
/*
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* drivers/cpufreq/cpufreq_ondemand.c
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*
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* Copyright (C) 2001 Russell King
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* (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
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* Jun Nakajima <jun.nakajima@intel.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 version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/cpufreq.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/kernel_stat.h>
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/percpu-defs.h>
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#include <linux/sysfs.h>
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#include <linux/tick.h>
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#include <linux/types.h>
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#include "cpufreq_governor.h"
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/* On-demand governor macors */
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#define DEF_FREQUENCY_DOWN_DIFFERENTIAL (10)
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#define DEF_FREQUENCY_UP_THRESHOLD (80)
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#define DEF_SAMPLING_DOWN_FACTOR (1)
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#define MAX_SAMPLING_DOWN_FACTOR (100000)
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#define MICRO_FREQUENCY_DOWN_DIFFERENTIAL (3)
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#define MICRO_FREQUENCY_UP_THRESHOLD (95)
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#define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
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#define MIN_FREQUENCY_UP_THRESHOLD (11)
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#define MAX_FREQUENCY_UP_THRESHOLD (100)
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static struct dbs_data od_dbs_data;
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static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info);
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#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
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static struct cpufreq_governor cpufreq_gov_ondemand;
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#endif
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static struct od_dbs_tuners od_tuners = {
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.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
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.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
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.down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
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.ignore_nice = 0,
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.powersave_bias = 0,
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};
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static void ondemand_powersave_bias_init_cpu(int cpu)
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{
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struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
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dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
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dbs_info->freq_lo = 0;
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}
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/*
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* Not all CPUs want IO time to be accounted as busy; this depends on how
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* efficient idling at a higher frequency/voltage is.
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* Pavel Machek says this is not so for various generations of AMD and old
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* Intel systems.
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* Mike Chan (androidlcom) calis this is also not true for ARM.
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* Because of this, whitelist specific known (series) of CPUs by default, and
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* leave all others up to the user.
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*/
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static int should_io_be_busy(void)
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{
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#if defined(CONFIG_X86)
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/*
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* For Intel, Core 2 (model 15) andl later have an efficient idle.
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*/
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if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
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boot_cpu_data.x86 == 6 &&
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boot_cpu_data.x86_model >= 15)
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return 1;
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#endif
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return 0;
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}
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/*
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* Find right freq to be set now with powersave_bias on.
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* Returns the freq_hi to be used right now and will set freq_hi_jiffies,
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* freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
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*/
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static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
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unsigned int freq_next, unsigned int relation)
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{
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unsigned int freq_req, freq_reduc, freq_avg;
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unsigned int freq_hi, freq_lo;
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unsigned int index = 0;
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unsigned int jiffies_total, jiffies_hi, jiffies_lo;
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struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
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policy->cpu);
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if (!dbs_info->freq_table) {
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dbs_info->freq_lo = 0;
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dbs_info->freq_lo_jiffies = 0;
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return freq_next;
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}
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cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
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relation, &index);
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freq_req = dbs_info->freq_table[index].frequency;
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freq_reduc = freq_req * od_tuners.powersave_bias / 1000;
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freq_avg = freq_req - freq_reduc;
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/* Find freq bounds for freq_avg in freq_table */
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index = 0;
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cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
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CPUFREQ_RELATION_H, &index);
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freq_lo = dbs_info->freq_table[index].frequency;
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index = 0;
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cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
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CPUFREQ_RELATION_L, &index);
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freq_hi = dbs_info->freq_table[index].frequency;
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/* Find out how long we have to be in hi and lo freqs */
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if (freq_hi == freq_lo) {
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dbs_info->freq_lo = 0;
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dbs_info->freq_lo_jiffies = 0;
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return freq_lo;
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}
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jiffies_total = usecs_to_jiffies(od_tuners.sampling_rate);
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jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
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jiffies_hi += ((freq_hi - freq_lo) / 2);
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jiffies_hi /= (freq_hi - freq_lo);
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jiffies_lo = jiffies_total - jiffies_hi;
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dbs_info->freq_lo = freq_lo;
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dbs_info->freq_lo_jiffies = jiffies_lo;
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dbs_info->freq_hi_jiffies = jiffies_hi;
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return freq_hi;
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}
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static void ondemand_powersave_bias_init(void)
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{
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int i;
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for_each_online_cpu(i) {
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ondemand_powersave_bias_init_cpu(i);
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}
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}
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static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
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{
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if (od_tuners.powersave_bias)
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freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
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else if (p->cur == p->max)
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return;
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__cpufreq_driver_target(p, freq, od_tuners.powersave_bias ?
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CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
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}
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/*
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* Every sampling_rate, we check, if current idle time is less than 20%
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* (default), then we try to increase frequency Every sampling_rate, we look for
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* a the lowest frequency which can sustain the load while keeping idle time
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* over 30%. If such a frequency exist, we try to decrease to this frequency.
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*
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* Any frequency increase takes it to the maximum frequency. Frequency reduction
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* happens at minimum steps of 5% (default) of current frequency
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*/
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static void od_check_cpu(int cpu, unsigned int load_freq)
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{
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struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
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struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
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dbs_info->freq_lo = 0;
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/* Check for frequency increase */
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if (load_freq > od_tuners.up_threshold * policy->cur) {
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/* If switching to max speed, apply sampling_down_factor */
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if (policy->cur < policy->max)
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dbs_info->rate_mult =
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od_tuners.sampling_down_factor;
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dbs_freq_increase(policy, policy->max);
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return;
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}
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/* Check for frequency decrease */
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/* if we cannot reduce the frequency anymore, break out early */
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if (policy->cur == policy->min)
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return;
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/*
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* The optimal frequency is the frequency that is the lowest that can
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* support the current CPU usage without triggering the up policy. To be
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* safe, we focus 10 points under the threshold.
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*/
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if (load_freq < (od_tuners.up_threshold - od_tuners.down_differential) *
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policy->cur) {
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unsigned int freq_next;
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freq_next = load_freq / (od_tuners.up_threshold -
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od_tuners.down_differential);
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/* No longer fully busy, reset rate_mult */
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dbs_info->rate_mult = 1;
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if (freq_next < policy->min)
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freq_next = policy->min;
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if (!od_tuners.powersave_bias) {
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__cpufreq_driver_target(policy, freq_next,
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CPUFREQ_RELATION_L);
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} else {
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int freq = powersave_bias_target(policy, freq_next,
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CPUFREQ_RELATION_L);
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__cpufreq_driver_target(policy, freq,
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CPUFREQ_RELATION_L);
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}
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}
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}
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static void od_dbs_timer(struct work_struct *work)
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{
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struct od_cpu_dbs_info_s *dbs_info =
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container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
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unsigned int cpu = dbs_info->cdbs.cpu;
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int delay, sample_type = dbs_info->sample_type;
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mutex_lock(&dbs_info->cdbs.timer_mutex);
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/* Common NORMAL_SAMPLE setup */
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dbs_info->sample_type = OD_NORMAL_SAMPLE;
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if (sample_type == OD_SUB_SAMPLE) {
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delay = dbs_info->freq_lo_jiffies;
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__cpufreq_driver_target(dbs_info->cdbs.cur_policy,
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dbs_info->freq_lo, CPUFREQ_RELATION_H);
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} else {
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dbs_check_cpu(&od_dbs_data, cpu);
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if (dbs_info->freq_lo) {
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/* Setup timer for SUB_SAMPLE */
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dbs_info->sample_type = OD_SUB_SAMPLE;
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delay = dbs_info->freq_hi_jiffies;
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} else {
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delay = delay_for_sampling_rate(od_tuners.sampling_rate
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* dbs_info->rate_mult);
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}
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}
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schedule_delayed_work_on(cpu, &dbs_info->cdbs.work, delay);
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mutex_unlock(&dbs_info->cdbs.timer_mutex);
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}
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/************************** sysfs interface ************************/
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static ssize_t show_sampling_rate_min(struct kobject *kobj,
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struct attribute *attr, char *buf)
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{
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return sprintf(buf, "%u\n", od_dbs_data.min_sampling_rate);
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}
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/**
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* update_sampling_rate - update sampling rate effective immediately if needed.
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* @new_rate: new sampling rate
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*
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* If new rate is smaller than the old, simply updaing
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* dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
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* original sampling_rate was 1 second and the requested new sampling rate is 10
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* ms because the user needs immediate reaction from ondemand governor, but not
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* sure if higher frequency will be required or not, then, the governor may
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* change the sampling rate too late; up to 1 second later. Thus, if we are
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* reducing the sampling rate, we need to make the new value effective
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* immediately.
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*/
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static void update_sampling_rate(unsigned int new_rate)
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{
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int cpu;
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od_tuners.sampling_rate = new_rate = max(new_rate,
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od_dbs_data.min_sampling_rate);
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for_each_online_cpu(cpu) {
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struct cpufreq_policy *policy;
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struct od_cpu_dbs_info_s *dbs_info;
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unsigned long next_sampling, appointed_at;
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policy = cpufreq_cpu_get(cpu);
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if (!policy)
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continue;
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if (policy->governor != &cpufreq_gov_ondemand) {
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cpufreq_cpu_put(policy);
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continue;
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}
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dbs_info = &per_cpu(od_cpu_dbs_info, policy->cpu);
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cpufreq_cpu_put(policy);
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mutex_lock(&dbs_info->cdbs.timer_mutex);
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if (!delayed_work_pending(&dbs_info->cdbs.work)) {
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mutex_unlock(&dbs_info->cdbs.timer_mutex);
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continue;
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}
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next_sampling = jiffies + usecs_to_jiffies(new_rate);
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appointed_at = dbs_info->cdbs.work.timer.expires;
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if (time_before(next_sampling, appointed_at)) {
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mutex_unlock(&dbs_info->cdbs.timer_mutex);
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cancel_delayed_work_sync(&dbs_info->cdbs.work);
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mutex_lock(&dbs_info->cdbs.timer_mutex);
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schedule_delayed_work_on(dbs_info->cdbs.cpu,
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&dbs_info->cdbs.work,
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usecs_to_jiffies(new_rate));
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}
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mutex_unlock(&dbs_info->cdbs.timer_mutex);
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}
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}
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static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1)
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return -EINVAL;
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update_sampling_rate(input);
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return count;
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}
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static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1)
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return -EINVAL;
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od_tuners.io_is_busy = !!input;
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return count;
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}
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static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
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input < MIN_FREQUENCY_UP_THRESHOLD) {
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return -EINVAL;
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}
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od_tuners.up_threshold = input;
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return count;
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}
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static ssize_t store_sampling_down_factor(struct kobject *a,
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struct attribute *b, const char *buf, size_t count)
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{
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unsigned int input, j;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
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return -EINVAL;
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od_tuners.sampling_down_factor = input;
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/* Reset down sampling multiplier in case it was active */
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for_each_online_cpu(j) {
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struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
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j);
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dbs_info->rate_mult = 1;
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}
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return count;
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}
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static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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unsigned int j;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1)
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return -EINVAL;
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if (input > 1)
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input = 1;
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if (input == od_tuners.ignore_nice) { /* nothing to do */
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return count;
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}
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od_tuners.ignore_nice = input;
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/* we need to re-evaluate prev_cpu_idle */
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for_each_online_cpu(j) {
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struct od_cpu_dbs_info_s *dbs_info;
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dbs_info = &per_cpu(od_cpu_dbs_info, j);
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dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
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&dbs_info->cdbs.prev_cpu_wall);
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if (od_tuners.ignore_nice)
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dbs_info->cdbs.prev_cpu_nice =
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kcpustat_cpu(j).cpustat[CPUTIME_NICE];
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}
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return count;
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}
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static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1)
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return -EINVAL;
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if (input > 1000)
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input = 1000;
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od_tuners.powersave_bias = input;
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ondemand_powersave_bias_init();
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return count;
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}
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show_one(od, sampling_rate, sampling_rate);
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show_one(od, io_is_busy, io_is_busy);
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show_one(od, up_threshold, up_threshold);
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show_one(od, sampling_down_factor, sampling_down_factor);
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show_one(od, ignore_nice_load, ignore_nice);
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show_one(od, powersave_bias, powersave_bias);
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|
|
|
define_one_global_rw(sampling_rate);
|
|
define_one_global_rw(io_is_busy);
|
|
define_one_global_rw(up_threshold);
|
|
define_one_global_rw(sampling_down_factor);
|
|
define_one_global_rw(ignore_nice_load);
|
|
define_one_global_rw(powersave_bias);
|
|
define_one_global_ro(sampling_rate_min);
|
|
|
|
static struct attribute *dbs_attributes[] = {
|
|
&sampling_rate_min.attr,
|
|
&sampling_rate.attr,
|
|
&up_threshold.attr,
|
|
&sampling_down_factor.attr,
|
|
&ignore_nice_load.attr,
|
|
&powersave_bias.attr,
|
|
&io_is_busy.attr,
|
|
NULL
|
|
};
|
|
|
|
static struct attribute_group od_attr_group = {
|
|
.attrs = dbs_attributes,
|
|
.name = "ondemand",
|
|
};
|
|
|
|
/************************** sysfs end ************************/
|
|
|
|
define_get_cpu_dbs_routines(od_cpu_dbs_info);
|
|
|
|
static struct od_ops od_ops = {
|
|
.io_busy = should_io_be_busy,
|
|
.powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
|
|
.powersave_bias_target = powersave_bias_target,
|
|
.freq_increase = dbs_freq_increase,
|
|
};
|
|
|
|
static struct dbs_data od_dbs_data = {
|
|
.governor = GOV_ONDEMAND,
|
|
.attr_group = &od_attr_group,
|
|
.tuners = &od_tuners,
|
|
.get_cpu_cdbs = get_cpu_cdbs,
|
|
.get_cpu_dbs_info_s = get_cpu_dbs_info_s,
|
|
.gov_dbs_timer = od_dbs_timer,
|
|
.gov_check_cpu = od_check_cpu,
|
|
.gov_ops = &od_ops,
|
|
};
|
|
|
|
static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
|
|
unsigned int event)
|
|
{
|
|
return cpufreq_governor_dbs(&od_dbs_data, policy, event);
|
|
}
|
|
|
|
#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
|
|
static
|
|
#endif
|
|
struct cpufreq_governor cpufreq_gov_ondemand = {
|
|
.name = "ondemand",
|
|
.governor = od_cpufreq_governor_dbs,
|
|
.max_transition_latency = TRANSITION_LATENCY_LIMIT,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
static int __init cpufreq_gov_dbs_init(void)
|
|
{
|
|
u64 idle_time;
|
|
int cpu = get_cpu();
|
|
|
|
mutex_init(&od_dbs_data.mutex);
|
|
idle_time = get_cpu_idle_time_us(cpu, NULL);
|
|
put_cpu();
|
|
if (idle_time != -1ULL) {
|
|
/* Idle micro accounting is supported. Use finer thresholds */
|
|
od_tuners.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
|
|
od_tuners.down_differential = MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
|
|
/*
|
|
* In nohz/micro accounting case we set the minimum frequency
|
|
* not depending on HZ, but fixed (very low). The deferred
|
|
* timer might skip some samples if idle/sleeping as needed.
|
|
*/
|
|
od_dbs_data.min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
|
|
} else {
|
|
/* For correct statistics, we need 10 ticks for each measure */
|
|
od_dbs_data.min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
|
|
jiffies_to_usecs(10);
|
|
}
|
|
|
|
return cpufreq_register_governor(&cpufreq_gov_ondemand);
|
|
}
|
|
|
|
static void __exit cpufreq_gov_dbs_exit(void)
|
|
{
|
|
cpufreq_unregister_governor(&cpufreq_gov_ondemand);
|
|
}
|
|
|
|
MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
|
|
MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
|
|
MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
|
|
"Low Latency Frequency Transition capable processors");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
|
|
fs_initcall(cpufreq_gov_dbs_init);
|
|
#else
|
|
module_init(cpufreq_gov_dbs_init);
|
|
#endif
|
|
module_exit(cpufreq_gov_dbs_exit);
|