linux/drivers/cpufreq/cpufreq_stats.c

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/*
* drivers/cpufreq/cpufreq_stats.c
*
* Copyright (C) 2003-2004 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
* (C) 2004 Zou Nan hai <nanhai.zou@intel.com>.
*
* 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.
*/
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/cputime.h>
static spinlock_t cpufreq_stats_lock;
struct cpufreq_stats {
unsigned int total_trans;
unsigned long long last_time;
unsigned int max_state;
unsigned int state_num;
unsigned int last_index;
u64 *time_in_state;
unsigned int *freq_table;
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
unsigned int *trans_table;
#endif
};
static int cpufreq_stats_update(struct cpufreq_stats *stats)
{
unsigned long long cur_time = get_jiffies_64();
spin_lock(&cpufreq_stats_lock);
stats->time_in_state[stats->last_index] += cur_time - stats->last_time;
stats->last_time = cur_time;
spin_unlock(&cpufreq_stats_lock);
return 0;
}
static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
{
return sprintf(buf, "%d\n", policy->stats->total_trans);
}
static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
{
struct cpufreq_stats *stats = policy->stats;
ssize_t len = 0;
int i;
cpufreq_stats_update(stats);
for (i = 0; i < stats->state_num; i++) {
len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],
(unsigned long long)
jiffies_64_to_clock_t(stats->time_in_state[i]));
}
return len;
}
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
{
struct cpufreq_stats *stats = policy->stats;
ssize_t len = 0;
int i, j;
len += snprintf(buf + len, PAGE_SIZE - len, " From : To\n");
len += snprintf(buf + len, PAGE_SIZE - len, " : ");
for (i = 0; i < stats->state_num; i++) {
if (len >= PAGE_SIZE)
break;
len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
stats->freq_table[i]);
}
if (len >= PAGE_SIZE)
return PAGE_SIZE;
len += snprintf(buf + len, PAGE_SIZE - len, "\n");
for (i = 0; i < stats->state_num; i++) {
if (len >= PAGE_SIZE)
break;
len += snprintf(buf + len, PAGE_SIZE - len, "%9u: ",
stats->freq_table[i]);
for (j = 0; j < stats->state_num; j++) {
if (len >= PAGE_SIZE)
break;
len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
stats->trans_table[i*stats->max_state+j]);
}
if (len >= PAGE_SIZE)
break;
len += snprintf(buf + len, PAGE_SIZE - len, "\n");
}
if (len >= PAGE_SIZE)
return PAGE_SIZE;
return len;
}
cpufreq_freq_attr_ro(trans_table);
#endif
cpufreq_freq_attr_ro(total_trans);
cpufreq_freq_attr_ro(time_in_state);
static struct attribute *default_attrs[] = {
&total_trans.attr,
&time_in_state.attr,
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
&trans_table.attr,
#endif
NULL
};
static struct attribute_group stats_attr_group = {
.attrs = default_attrs,
.name = "stats"
};
static int freq_table_get_index(struct cpufreq_stats *stats, unsigned int freq)
{
int index;
for (index = 0; index < stats->max_state; index++)
if (stats->freq_table[index] == freq)
return index;
return -1;
}
static void __cpufreq_stats_free_table(struct cpufreq_policy *policy)
{
struct cpufreq_stats *stats = policy->stats;
/* Already freed */
if (!stats)
return;
pr_debug("%s: Free stats table\n", __func__);
sysfs_remove_group(&policy->kobj, &stats_attr_group);
kfree(stats->time_in_state);
kfree(stats);
policy->stats = NULL;
}
static void cpufreq_stats_free_table(unsigned int cpu)
{
struct cpufreq_policy *policy;
policy = cpufreq_cpu_get(cpu);
if (!policy)
return;
__cpufreq_stats_free_table(policy);
cpufreq_cpu_put(policy);
}
static int __cpufreq_stats_create_table(struct cpufreq_policy *policy)
{
unsigned int i = 0, count = 0, ret = -ENOMEM;
struct cpufreq_stats *stats;
unsigned int alloc_size;
unsigned int cpu = policy->cpu;
struct cpufreq_frequency_table *pos, *table;
/* We need cpufreq table for creating stats table */
table = cpufreq_frequency_get_table(cpu);
if (unlikely(!table))
return 0;
/* stats already initialized */
if (policy->stats)
return -EEXIST;
stats = kzalloc(sizeof(*stats), GFP_KERNEL);
if (!stats)
return -ENOMEM;
/* Find total allocation size */
cpufreq_for_each_valid_entry(pos, table)
count++;
alloc_size = count * sizeof(int) + count * sizeof(u64);
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
alloc_size += count * count * sizeof(int);
#endif
/* Allocate memory for time_in_state/freq_table/trans_table in one go */
stats->time_in_state = kzalloc(alloc_size, GFP_KERNEL);
if (!stats->time_in_state)
goto free_stat;
stats->freq_table = (unsigned int *)(stats->time_in_state + count);
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
stats->trans_table = stats->freq_table + count;
#endif
stats->max_state = count;
/* Find valid-unique entries */
cpufreq_for_each_valid_entry(pos, table)
if (freq_table_get_index(stats, pos->frequency) == -1)
stats->freq_table[i++] = pos->frequency;
stats->state_num = i;
stats->last_time = get_jiffies_64();
stats->last_index = freq_table_get_index(stats, policy->cur);
policy->stats = stats;
ret = sysfs_create_group(&policy->kobj, &stats_attr_group);
if (!ret)
return 0;
/* We failed, release resources */
policy->stats = NULL;
kfree(stats->time_in_state);
free_stat:
kfree(stats);
return ret;
}
static void cpufreq_stats_create_table(unsigned int cpu)
{
struct cpufreq_policy *policy;
/*
* "likely(!policy)" because normally cpufreq_stats will be registered
* before cpufreq driver
*/
policy = cpufreq_cpu_get(cpu);
if (likely(!policy))
return;
__cpufreq_stats_create_table(policy);
cpufreq_cpu_put(policy);
}
static int cpufreq_stat_notifier_policy(struct notifier_block *nb,
unsigned long val, void *data)
{
cpufreq: stats: handle cpufreq_unregister_driver() and suspend/resume properly There are several problems with cpufreq stats in the way it handles cpufreq_unregister_driver() and suspend/resume.. - We must not lose data collected so far when suspend/resume happens and so stats directories must not be removed/allocated during these operations, which is done currently. - cpufreq_stat has registered notifiers with both cpufreq and hotplug. It adds sysfs stats directory with a cpufreq notifier: CPUFREQ_NOTIFY and removes this directory with a notifier from hotplug core. In case cpufreq_unregister_driver() is called (on rmmod cpufreq driver), stats directories per cpu aren't removed as CPUs are still online. The only call cpufreq_stats gets is cpufreq_stats_update_policy_cpu() for all CPUs except the last of each policy. And pointer to stat information is stored in the entry for last CPU in the per-cpu cpufreq_stats_table. But policy structure would be freed inside cpufreq core and so that will result in memory leak inside cpufreq stats (as we are never freeing memory for stats). Now if we again insert the module cpufreq_register_driver() will be called and we will again allocate stats data and put it on for first CPU of every policy. In case we only have a single CPU per policy, we will return with a error from cpufreq_stats_create_table() due to this code: if (per_cpu(cpufreq_stats_table, cpu)) return -EBUSY; And so probably cpufreq stats directory would not show up anymore (as it was added inside last policies->kobj which doesn't exist anymore). I haven't tested it, though. Also the values in stats files wouldn't be refreshed as we are using the earlier stats structure. - CPUFREQ_NOTIFY is called from cpufreq_set_policy() which is called for scenarios where we don't really want cpufreq_stat_notifier_policy() to get called. For example whenever we are changing anything related to a policy: min/max/current freq, etc. cpufreq_set_policy() is called and so cpufreq stats is notified. Where we don't do any useful stuff other than simply returning with -EBUSY from cpufreq_stats_create_table(). And so this isn't the right notifier that cpufreq stats.. Due to all above reasons this patch does following changes: - Add new notifiers CPUFREQ_CREATE_POLICY and CPUFREQ_REMOVE_POLICY, which are only called when policy is created/destroyed. They aren't called for suspend/resume paths.. - Use these notifiers in cpufreq_stat_notifier_policy() to create/destory stats sysfs entries. And so cpufreq_unregister_driver() or suspend/resume shouldn't be a problem for cpufreq_stats. - Return early from cpufreq_stat_cpu_callback() for suspend/resume sequence, so that we don't free stats structure. Acked-by: Nicolas Pitre <nico@linaro.org> Tested-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-01-07 01:40:10 +00:00
int ret = 0;
struct cpufreq_policy *policy = data;
cpufreq: stats: handle cpufreq_unregister_driver() and suspend/resume properly There are several problems with cpufreq stats in the way it handles cpufreq_unregister_driver() and suspend/resume.. - We must not lose data collected so far when suspend/resume happens and so stats directories must not be removed/allocated during these operations, which is done currently. - cpufreq_stat has registered notifiers with both cpufreq and hotplug. It adds sysfs stats directory with a cpufreq notifier: CPUFREQ_NOTIFY and removes this directory with a notifier from hotplug core. In case cpufreq_unregister_driver() is called (on rmmod cpufreq driver), stats directories per cpu aren't removed as CPUs are still online. The only call cpufreq_stats gets is cpufreq_stats_update_policy_cpu() for all CPUs except the last of each policy. And pointer to stat information is stored in the entry for last CPU in the per-cpu cpufreq_stats_table. But policy structure would be freed inside cpufreq core and so that will result in memory leak inside cpufreq stats (as we are never freeing memory for stats). Now if we again insert the module cpufreq_register_driver() will be called and we will again allocate stats data and put it on for first CPU of every policy. In case we only have a single CPU per policy, we will return with a error from cpufreq_stats_create_table() due to this code: if (per_cpu(cpufreq_stats_table, cpu)) return -EBUSY; And so probably cpufreq stats directory would not show up anymore (as it was added inside last policies->kobj which doesn't exist anymore). I haven't tested it, though. Also the values in stats files wouldn't be refreshed as we are using the earlier stats structure. - CPUFREQ_NOTIFY is called from cpufreq_set_policy() which is called for scenarios where we don't really want cpufreq_stat_notifier_policy() to get called. For example whenever we are changing anything related to a policy: min/max/current freq, etc. cpufreq_set_policy() is called and so cpufreq stats is notified. Where we don't do any useful stuff other than simply returning with -EBUSY from cpufreq_stats_create_table(). And so this isn't the right notifier that cpufreq stats.. Due to all above reasons this patch does following changes: - Add new notifiers CPUFREQ_CREATE_POLICY and CPUFREQ_REMOVE_POLICY, which are only called when policy is created/destroyed. They aren't called for suspend/resume paths.. - Use these notifiers in cpufreq_stat_notifier_policy() to create/destory stats sysfs entries. And so cpufreq_unregister_driver() or suspend/resume shouldn't be a problem for cpufreq_stats. - Return early from cpufreq_stat_cpu_callback() for suspend/resume sequence, so that we don't free stats structure. Acked-by: Nicolas Pitre <nico@linaro.org> Tested-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-01-07 01:40:10 +00:00
if (val == CPUFREQ_CREATE_POLICY)
ret = __cpufreq_stats_create_table(policy);
else if (val == CPUFREQ_REMOVE_POLICY)
__cpufreq_stats_free_table(policy);
cpufreq: stats: handle cpufreq_unregister_driver() and suspend/resume properly There are several problems with cpufreq stats in the way it handles cpufreq_unregister_driver() and suspend/resume.. - We must not lose data collected so far when suspend/resume happens and so stats directories must not be removed/allocated during these operations, which is done currently. - cpufreq_stat has registered notifiers with both cpufreq and hotplug. It adds sysfs stats directory with a cpufreq notifier: CPUFREQ_NOTIFY and removes this directory with a notifier from hotplug core. In case cpufreq_unregister_driver() is called (on rmmod cpufreq driver), stats directories per cpu aren't removed as CPUs are still online. The only call cpufreq_stats gets is cpufreq_stats_update_policy_cpu() for all CPUs except the last of each policy. And pointer to stat information is stored in the entry for last CPU in the per-cpu cpufreq_stats_table. But policy structure would be freed inside cpufreq core and so that will result in memory leak inside cpufreq stats (as we are never freeing memory for stats). Now if we again insert the module cpufreq_register_driver() will be called and we will again allocate stats data and put it on for first CPU of every policy. In case we only have a single CPU per policy, we will return with a error from cpufreq_stats_create_table() due to this code: if (per_cpu(cpufreq_stats_table, cpu)) return -EBUSY; And so probably cpufreq stats directory would not show up anymore (as it was added inside last policies->kobj which doesn't exist anymore). I haven't tested it, though. Also the values in stats files wouldn't be refreshed as we are using the earlier stats structure. - CPUFREQ_NOTIFY is called from cpufreq_set_policy() which is called for scenarios where we don't really want cpufreq_stat_notifier_policy() to get called. For example whenever we are changing anything related to a policy: min/max/current freq, etc. cpufreq_set_policy() is called and so cpufreq stats is notified. Where we don't do any useful stuff other than simply returning with -EBUSY from cpufreq_stats_create_table(). And so this isn't the right notifier that cpufreq stats.. Due to all above reasons this patch does following changes: - Add new notifiers CPUFREQ_CREATE_POLICY and CPUFREQ_REMOVE_POLICY, which are only called when policy is created/destroyed. They aren't called for suspend/resume paths.. - Use these notifiers in cpufreq_stat_notifier_policy() to create/destory stats sysfs entries. And so cpufreq_unregister_driver() or suspend/resume shouldn't be a problem for cpufreq_stats. - Return early from cpufreq_stat_cpu_callback() for suspend/resume sequence, so that we don't free stats structure. Acked-by: Nicolas Pitre <nico@linaro.org> Tested-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-01-07 01:40:10 +00:00
return ret;
}
static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
unsigned long val, void *data)
{
struct cpufreq_freqs *freq = data;
struct cpufreq_policy *policy = cpufreq_cpu_get(freq->cpu);
struct cpufreq_stats *stats;
int old_index, new_index;
if (!policy) {
pr_err("%s: No policy found\n", __func__);
return 0;
}
if (val != CPUFREQ_POSTCHANGE)
goto put_policy;
if (!policy->stats) {
pr_debug("%s: No stats found\n", __func__);
goto put_policy;
}
stats = policy->stats;
old_index = stats->last_index;
new_index = freq_table_get_index(stats, freq->new);
/* We can't do stats->time_in_state[-1]= .. */
[CPUFREQ] Don't set stat->last_index to -1 if the pol->cur has incorrect value. If the driver submitted an non-existing pol>cur value (say it used the default initialized value of zero), when the cpufreq stats tries to setup its initial values it incorrectly sets stat->last_index to -1 (or 0xfffff...). And cpufreq_stats_update tries to update at that index location and fails. This can be caused by: stat->last_index = freq_table_get_index(stat, policy->cur); not finding the appropiate frequency in the table (b/c the policy->cur is wrong) and we end up crashing. The fix however is concentrated in the 'cpufreq_stats_update' as the last_index (and old_index) are updated there. Which means it can reset the last_index to -1 again and on the next iteration cause a crash. Without this patch, the following crash is observed: powernow-k8: Found 1 AMD Athlon(tm) 64 Processor 3700+ (1 cpu cores) (version 2.20.00) powernow-k8: fid 0x2 (1000 MHz), vid 0x12 powernow-k8: fid 0xa (1800 MHz), vid 0xa powernow-k8: fid 0xc (2000 MHz), vid 0x8 powernow-k8: fid 0xe (2200 MHz), vid 0x8 Marking TSC unstable due to cpufreq changes powernow-k8: fid trans failed, fid 0x2, curr 0x0 BUG: unable to handle kernel paging request at ffff880807e07b78 IP: [<ffffffff81479163>] cpufreq_stats_update+0x46/0x5b .. snip.. Pid: 1, comm: swapper Not tainted 3.0.0-rc2 #45 MICRO-STAR INTERNATIONAL CO., LTD MS-7094/MS-7094 ..snip.. Call Trace: [<ffffffff81479248>] cpufreq_stat_notifier_trans+0x48/0x7c [<ffffffff81095d68>] notifier_call_chain+0x32/0x5e [<ffffffff81095e6b>] __srcu_notifier_call_chain+0x47/0x63 [<ffffffff81095e96>] srcu_notifier_call_chain+0xf/0x11 [<ffffffff81477e7a>] cpufreq_notify_transition+0x111/0x134 [<ffffffff8147b0d4>] powernowk8_target+0x53b/0x617 [<ffffffff8147723a>] __cpufreq_driver_target+0x2e/0x30 [<ffffffff8147a127>] cpufreq_governor_dbs+0x339/0x356 [<ffffffff81477394>] __cpufreq_governor+0xa8/0xe9 [<ffffffff81477525>] __cpufreq_set_policy+0x132/0x13e [<ffffffff8147848d>] cpufreq_add_dev_interface+0x272/0x28c Reported-by: Tobias Diedrich <ranma+xen@tdiedrich.de> Tested-by: Tobias Diedrich <ranma+xen@tdiedrich.de> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Dave Jones <davej@redhat.com>
2011-06-16 19:36:38 +00:00
if (old_index == -1 || new_index == -1)
goto put_policy;
[CPUFREQ] Don't set stat->last_index to -1 if the pol->cur has incorrect value. If the driver submitted an non-existing pol>cur value (say it used the default initialized value of zero), when the cpufreq stats tries to setup its initial values it incorrectly sets stat->last_index to -1 (or 0xfffff...). And cpufreq_stats_update tries to update at that index location and fails. This can be caused by: stat->last_index = freq_table_get_index(stat, policy->cur); not finding the appropiate frequency in the table (b/c the policy->cur is wrong) and we end up crashing. The fix however is concentrated in the 'cpufreq_stats_update' as the last_index (and old_index) are updated there. Which means it can reset the last_index to -1 again and on the next iteration cause a crash. Without this patch, the following crash is observed: powernow-k8: Found 1 AMD Athlon(tm) 64 Processor 3700+ (1 cpu cores) (version 2.20.00) powernow-k8: fid 0x2 (1000 MHz), vid 0x12 powernow-k8: fid 0xa (1800 MHz), vid 0xa powernow-k8: fid 0xc (2000 MHz), vid 0x8 powernow-k8: fid 0xe (2200 MHz), vid 0x8 Marking TSC unstable due to cpufreq changes powernow-k8: fid trans failed, fid 0x2, curr 0x0 BUG: unable to handle kernel paging request at ffff880807e07b78 IP: [<ffffffff81479163>] cpufreq_stats_update+0x46/0x5b .. snip.. Pid: 1, comm: swapper Not tainted 3.0.0-rc2 #45 MICRO-STAR INTERNATIONAL CO., LTD MS-7094/MS-7094 ..snip.. Call Trace: [<ffffffff81479248>] cpufreq_stat_notifier_trans+0x48/0x7c [<ffffffff81095d68>] notifier_call_chain+0x32/0x5e [<ffffffff81095e6b>] __srcu_notifier_call_chain+0x47/0x63 [<ffffffff81095e96>] srcu_notifier_call_chain+0xf/0x11 [<ffffffff81477e7a>] cpufreq_notify_transition+0x111/0x134 [<ffffffff8147b0d4>] powernowk8_target+0x53b/0x617 [<ffffffff8147723a>] __cpufreq_driver_target+0x2e/0x30 [<ffffffff8147a127>] cpufreq_governor_dbs+0x339/0x356 [<ffffffff81477394>] __cpufreq_governor+0xa8/0xe9 [<ffffffff81477525>] __cpufreq_set_policy+0x132/0x13e [<ffffffff8147848d>] cpufreq_add_dev_interface+0x272/0x28c Reported-by: Tobias Diedrich <ranma+xen@tdiedrich.de> Tested-by: Tobias Diedrich <ranma+xen@tdiedrich.de> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Dave Jones <davej@redhat.com>
2011-06-16 19:36:38 +00:00
if (old_index == new_index)
goto put_policy;
cpufreq_stats_update(stats);
stats->last_index = new_index;
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
stats->trans_table[old_index * stats->max_state + new_index]++;
#endif
stats->total_trans++;
put_policy:
cpufreq_cpu_put(policy);
return 0;
}
static struct notifier_block notifier_policy_block = {
.notifier_call = cpufreq_stat_notifier_policy
};
static struct notifier_block notifier_trans_block = {
.notifier_call = cpufreq_stat_notifier_trans
};
static int __init cpufreq_stats_init(void)
{
int ret;
unsigned int cpu;
[PATCH] create and destroy cpufreq sysfs entries based on cpu notifiers cpufreq entries in sysfs should only be populated when CPU is online state. When we either boot with maxcpus=x and then boot the other cpus by echoing to sysfs online file, these entries should be created and destroyed when CPU_DEAD is notified. Same treatement as cache entries under sysfs. We place the processor in the lowest frequency, so hw managed P-State transitions can still work on the other threads to save power. Primary goal was to just make these directories appear/disapper dynamically. There is one in this patch i had to do, which i really dont like myself but probably best if someone handling the cpufreq infrastructure could give this code right treatment if this is not acceptable. I guess its probably good for the first cut. - Converting lock_cpu_hotplug()/unlock_cpu_hotplug() to disable/enable preempt. The locking was smack in the middle of the notification path, when the hotplug is already holding the lock. I tried another solution to avoid this so avoid taking locks if we know we are from notification path. The solution was getting very ugly and i decided this was probably good for this iteration until someone who understands cpufreq could do a better job than me. (akpm: export cpucontrol to GPL modules: drivers/cpufreq/cpufreq_stats.c now does lock_cpu_hotplug()) Signed-off-by: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: Zwane Mwaikambo <zwane@holomorphy.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 22:59:54 +00:00
spin_lock_init(&cpufreq_stats_lock);
ret = cpufreq_register_notifier(&notifier_policy_block,
CPUFREQ_POLICY_NOTIFIER);
if (ret)
return ret;
for_each_online_cpu(cpu)
cpufreq_stats_create_table(cpu);
ret = cpufreq_register_notifier(&notifier_trans_block,
CPUFREQ_TRANSITION_NOTIFIER);
if (ret) {
cpufreq_unregister_notifier(&notifier_policy_block,
CPUFREQ_POLICY_NOTIFIER);
for_each_online_cpu(cpu)
cpufreq_stats_free_table(cpu);
return ret;
}
return 0;
}
static void __exit cpufreq_stats_exit(void)
{
unsigned int cpu;
[PATCH] create and destroy cpufreq sysfs entries based on cpu notifiers cpufreq entries in sysfs should only be populated when CPU is online state. When we either boot with maxcpus=x and then boot the other cpus by echoing to sysfs online file, these entries should be created and destroyed when CPU_DEAD is notified. Same treatement as cache entries under sysfs. We place the processor in the lowest frequency, so hw managed P-State transitions can still work on the other threads to save power. Primary goal was to just make these directories appear/disapper dynamically. There is one in this patch i had to do, which i really dont like myself but probably best if someone handling the cpufreq infrastructure could give this code right treatment if this is not acceptable. I guess its probably good for the first cut. - Converting lock_cpu_hotplug()/unlock_cpu_hotplug() to disable/enable preempt. The locking was smack in the middle of the notification path, when the hotplug is already holding the lock. I tried another solution to avoid this so avoid taking locks if we know we are from notification path. The solution was getting very ugly and i decided this was probably good for this iteration until someone who understands cpufreq could do a better job than me. (akpm: export cpucontrol to GPL modules: drivers/cpufreq/cpufreq_stats.c now does lock_cpu_hotplug()) Signed-off-by: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: Zwane Mwaikambo <zwane@holomorphy.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 22:59:54 +00:00
cpufreq_unregister_notifier(&notifier_policy_block,
CPUFREQ_POLICY_NOTIFIER);
cpufreq_unregister_notifier(&notifier_trans_block,
CPUFREQ_TRANSITION_NOTIFIER);
for_each_online_cpu(cpu)
cpufreq_stats_free_table(cpu);
}
MODULE_AUTHOR("Zou Nan hai <nanhai.zou@intel.com>");
MODULE_DESCRIPTION("Export cpufreq stats via sysfs");
MODULE_LICENSE("GPL");
module_init(cpufreq_stats_init);
module_exit(cpufreq_stats_exit);