[PATCH v2] cpufreq: stats: Add 'load_table' debugfs file to showaccumulated data of CPUs

From: Chanwoo Choi
Date: Thu Jun 20 2013 - 04:22:30 EST

This patch add new 'load_table' debugfs file to show previous accumulated data
of CPUs load as following path and add CPUFREQ_LOADCHECK notification to
CPUFREQ_TRANSITION_NOTIFIER notifier chain.
- /sys/kernel/debug/cpufreq/load_table

When governor calculates CPUs load on dbs_check_cpu(), governor send
CPUFREQ_LOADCHECK notification with CPUs load, so that cpufreq_stats
accumulates calculated CPUs load on 'load_table' storage.

This debugfs file is used to judge the correct system state or determine
suitable system resource according to current CPUs load on user-space.

This debugfs file include following data:
- Measurement point of time
- CPU frequency
- Per-CPU load

Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Signed-off-by: Myungjoo Ham <myungjoo.ham@xxxxxxxxxxx>
---
Changes since v1:
- Set maximum storage size to save CPUs load on Kconfig
- Use spinlock to synchronize read/write operation for CPUs load
- Use local variable instead of global variable(struct cpufreq_freqs *freqs)
- Use pointer of data structure to get correct size of data structure
in sizeof() macro instead of structure name
: sizeof(struct cpufreq_freqs) -> sizeof(*stat->load_table)
- Change time unit from nanosecond to microsecond
- Remove unnecessary memory copy

drivers/cpufreq/Kconfig | 6 ++
drivers/cpufreq/cpufreq.c | 4 +
drivers/cpufreq/cpufreq_governor.c | 19 +++-
drivers/cpufreq/cpufreq_stats.c | 192 +++++++++++++++++++++++++++++++++----
include/linux/cpufreq.h | 6 ++
5 files changed, 206 insertions(+), 21 deletions(-)

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 534fcb8..8a429b3 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -45,6 +45,12 @@ config CPU_FREQ_STAT_DETAILS

If in doubt, say N.

+config NR_CPU_LOAD_STORAGE
+ int "Maximum storage size to save CPU load (10-100)"
+ range 10 100
+ depends on CPU_FREQ_STAT_DETAILS
+ default "10"
+
choice
prompt "Default CPUFreq governor"
default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 2d53f47..cbaaff0 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -292,6 +292,10 @@ void __cpufreq_notify_transition(struct cpufreq_policy *policy,
if (likely(policy) && likely(policy->cpu == freqs->cpu))
policy->cur = freqs->new;
break;
+ case CPUFREQ_LOADCHECK:
+ srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
+ CPUFREQ_LOADCHECK, freqs);
+ break;
}
}
/**
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index dc9b72e..bca341b 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -90,6 +90,9 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
unsigned int max_load = 0;
unsigned int ignore_nice;
unsigned int j;
+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ struct cpufreq_freqs freq;
+#endif

if (dbs_data->cdata->governor == GOV_ONDEMAND)
ignore_nice = od_tuners->ignore_nice;
@@ -144,11 +147,17 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
idle_time += jiffies_to_usecs(cur_nice_jiffies);
}

- if (unlikely(!wall_time || wall_time < idle_time))
+ if (unlikely(!wall_time || wall_time < idle_time)) {
+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ freq.load[j] = 0;
+#endif
continue;
+ }

load = 100 * (wall_time - idle_time) / wall_time;
-
+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ freq.load[j] = load;
+#endif
if (dbs_data->cdata->governor == GOV_ONDEMAND) {
int freq_avg = __cpufreq_driver_getavg(policy, j);
if (freq_avg <= 0)
@@ -161,6 +170,12 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
max_load = load;
}

+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ freq.time = ktime_to_ms(ktime_get());
+ freq.old = freq.new = policy->cur;
+
+ cpufreq_notify_transition(policy, &freq, CPUFREQ_LOADCHECK);
+#endif
dbs_data->cdata->gov_check_cpu(cpu, max_load);
}
EXPORT_SYMBOL_GPL(dbs_check_cpu);
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index fb65dec..289d675 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -12,6 +12,7 @@
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/cpu.h>
+#include <linux/debugfs.h>
#include <linux/sysfs.h>
#include <linux/cpufreq.h>
#include <linux/module.h>
@@ -23,6 +24,7 @@
#include <asm/cputime.h>

static spinlock_t cpufreq_stats_lock;
+static spinlock_t cpufreq_stats_lock_load_table;

struct cpufreq_stats {
unsigned int cpu;
@@ -35,6 +37,12 @@ struct cpufreq_stats {
unsigned int *freq_table;
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
unsigned int *trans_table;
+
+ /* debugfs file for load_table */
+ struct cpufreq_freqs *load_table;
+ unsigned int load_last_index;
+ unsigned int load_max_index;
+ struct dentry *debugfs_cpufreq;
#endif
};

@@ -149,6 +157,134 @@ static struct attribute_group stats_attr_group = {
.name = "stats"
};

+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+#define MAX_LINE_SIZE 255
+static ssize_t load_table_read(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ struct cpufreq_policy *policy = file->private_data;
+ struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
+ struct cpufreq_freqs *load_table = stat->load_table;
+ unsigned int alloc_size_buf;
+ ssize_t len = 0;
+ char *buf;
+ int i, j, ret;
+
+ alloc_size_buf = MAX_LINE_SIZE * stat->load_max_index;
+ buf = kzalloc(alloc_size_buf, GFP_KERNEL);
+ if (!buf)
+ return 0;
+
+ spin_lock(&cpufreq_stats_lock_load_table);
+ len += sprintf(buf + len, "%10s %10s", "Time", "Frequency");
+ for (j = 0; j < NR_CPUS; j++)
+ len += sprintf(buf + len, " %3s%d", "cpu", j);
+ len += sprintf(buf + len, "\n");
+
+ i = stat->load_last_index;
+ do {
+ len += sprintf(buf + len, "%10lld %10d",
+ load_table[i].time,
+ load_table[i].old);
+
+ for (j = 0; j < NR_CPUS; j++)
+ len += sprintf(buf + len, " %4d",
+ load_table[i].load[j]);
+ len += sprintf(buf + len, "\n");
+
+ if (++i == stat->load_max_index)
+ i = 0;
+ } while (i != stat->load_last_index);
+ spin_unlock(&cpufreq_stats_lock_load_table);
+
+ ret = simple_read_from_buffer(user_buf, count, ppos, buf, len);
+ kfree(buf);
+
+ return ret;
+}
+
+static const struct file_operations load_table_fops = {
+ .read = load_table_read,
+ .open = simple_open,
+ .llseek = no_llseek,
+};
+
+static void cpufreq_stats_store_load_table(struct cpufreq_freqs *freq)
+{
+ struct cpufreq_stats *stat;
+ int i, last_index;
+
+ stat = per_cpu(cpufreq_stats_table, freq->cpu);
+ if (!stat)
+ return;
+
+ spin_lock(&cpufreq_stats_lock_load_table);
+ last_index = stat->load_last_index;
+ stat->load_table[last_index].old = freq->old;
+ stat->load_table[last_index].time = freq->time;
+ for (i = 0; i < NR_CPUS; i++)
+ stat->load_table[last_index].load[i] = freq->load[i];
+
+ if (++stat->load_last_index == stat->load_max_index)
+ stat->load_last_index = 0;
+ spin_unlock(&cpufreq_stats_lock_load_table);
+}
+
+static int cpufreq_stats_create_debugfs(struct cpufreq_policy *policy)
+{
+ struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
+ unsigned int alloc_size_load;
+ int ret = 0;
+
+ stat->load_last_index = 0;
+ stat->load_max_index = CONFIG_NR_CPU_LOAD_STORAGE;
+ alloc_size_load = sizeof(*stat->load_table) * stat->load_max_index;
+ stat->load_table = kzalloc(alloc_size_load, GFP_KERNEL);
+ if (!stat->load_table) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ stat->debugfs_cpufreq = debugfs_create_dir("cpufreq", NULL);
+ if (!stat->debugfs_cpufreq) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ debugfs_create_file("load_table", S_IWUSR, stat->debugfs_cpufreq,
+ (void *)policy, &load_table_fops);
+err:
+ return ret;
+}
+
+static void cpufreq_stats_free_debugfs(unsigned int cpu)
+{
+ struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+ struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, cpu);
+
+ if (!policy)
+ return;
+
+ if (!policy_is_shared(policy)) {
+ pr_debug("%s: Free debugfs stat\n", __func__);
+ debugfs_remove(stat->debugfs_cpufreq);
+ }
+}
+#else
+static void cpufreq_stats_store_load_table(struct cpufreq_freqs *freq)
+{
+ return 0;
+}
+static int cpufreq_stats_create_debugfs(struct cpufreq_policy *policy)
+{
+ return 0;
+}
+static void cpufreq_stats_free_debugfs(unsigned int cpu)
+{
+ return;
+}
+#endif
+
static int freq_table_get_index(struct cpufreq_stats *stat, unsigned int freq)
{
int index;
@@ -167,6 +303,9 @@ static void cpufreq_stats_free_table(unsigned int cpu)

if (stat) {
pr_debug("%s: Free stat table\n", __func__);
+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ kfree(stat->load_table);
+#endif
kfree(stat->time_in_state);
kfree(stat);
per_cpu(cpufreq_stats_table, cpu) = NULL;
@@ -257,6 +396,13 @@ static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
spin_lock(&cpufreq_stats_lock);
stat->last_time = get_jiffies_64();
stat->last_index = freq_table_get_index(stat, policy->cur);
+
+ ret = cpufreq_stats_create_debugfs(data);
+ if (ret) {
+ ret = -EINVAL;
+ goto error_out;
+ }
+
spin_unlock(&cpufreq_stats_lock);
cpufreq_cpu_put(data);
return 0;
@@ -312,32 +458,38 @@ static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
struct cpufreq_stats *stat;
int old_index, new_index;

- if (val != CPUFREQ_POSTCHANGE)
- return 0;
-
- stat = per_cpu(cpufreq_stats_table, freq->cpu);
- if (!stat)
- return 0;
+ switch (val) {
+ case CPUFREQ_POSTCHANGE:
+ stat = per_cpu(cpufreq_stats_table, freq->cpu);
+ if (!stat)
+ return 0;

- old_index = stat->last_index;
- new_index = freq_table_get_index(stat, freq->new);
+ old_index = stat->last_index;
+ new_index = freq_table_get_index(stat, freq->new);

- /* We can't do stat->time_in_state[-1]= .. */
- if (old_index == -1 || new_index == -1)
- return 0;
+ /* We can't do stat->time_in_state[-1]= .. */
+ if (old_index == -1 || new_index == -1)
+ return 0;

- cpufreq_stats_update(freq->cpu);
+ cpufreq_stats_update(freq->cpu);

- if (old_index == new_index)
- return 0;
+ if (old_index == new_index)
+ return 0;

- spin_lock(&cpufreq_stats_lock);
- stat->last_index = new_index;
+ spin_lock(&cpufreq_stats_lock);
+ stat->last_index = new_index;
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
- stat->trans_table[old_index * stat->max_state + new_index]++;
+ stat->trans_table[old_index * stat->max_state + new_index]++;
#endif
- stat->total_trans++;
- spin_unlock(&cpufreq_stats_lock);
+ stat->total_trans++;
+ spin_unlock(&cpufreq_stats_lock);
+
+ break;
+ case CPUFREQ_LOADCHECK:
+ cpufreq_stats_store_load_table(freq);
+ break;
+ }
+
return 0;
}

@@ -352,12 +504,14 @@ static int __cpuinit cpufreq_stat_cpu_callback(struct notifier_block *nfb,
cpufreq_update_policy(cpu);
break;
case CPU_DOWN_PREPARE:
+ cpufreq_stats_free_debugfs(cpu);
cpufreq_stats_free_sysfs(cpu);
break;
case CPU_DEAD:
cpufreq_stats_free_table(cpu);
break;
case CPU_UP_CANCELED_FROZEN:
+ cpufreq_stats_free_debugfs(cpu);
cpufreq_stats_free_sysfs(cpu);
cpufreq_stats_free_table(cpu);
break;
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 037d36a..f780645 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -140,12 +140,18 @@ static inline bool policy_is_shared(struct cpufreq_policy *policy)
#define CPUFREQ_POSTCHANGE (1)
#define CPUFREQ_RESUMECHANGE (8)
#define CPUFREQ_SUSPENDCHANGE (9)
+#define CPUFREQ_LOADCHECK (10)

struct cpufreq_freqs {
unsigned int cpu; /* cpu nr */
unsigned int old;
unsigned int new;
u8 flags; /* flags of cpufreq_driver, see below. */
+
+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ int64_t time;
+ unsigned int load[NR_CPUS];
+#endif
};


--
1.8.0

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