[RESEND][PATCH] cpufreq: stats: Add 'load_table' sysfs file to showaccumulated data of CPU

From: Chanwoo Choi
Date: Wed Jun 05 2013 - 04:11:42 EST

This patch add new sysfs file to show previous accumulated data of CPU load
as following path. This sysfs file is used to judge the correct system state
or determine suitable system resource on user-space.
- /sys/devices/system/cpu/cpu0/cpufreq/stats/load_table

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

Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
Signed-off-by: Myungjoo Ham <myungjoo.ham@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---

Additionally, I explain an example using 'load_table' sysfs entry.

Exynos4412 series has Quad-core and all cores share the power-line.
I cann't set diffent voltage/frequency to each CPU. To reduce power-
consumption, I certainly have to turn on/off CPU online state
according to CPU load on runtime. As a result, I peridically need to
monitor current cpu state to determine a proper amount of system
resource(necessary number of online cpu) and to delete wasted power.
So, I need 'load_table' sysfs file to monitor current cpu state.

I add a table which show power consumption of target based on
Exynos4412 SoC. This table indicate the difference power-consumption
according to a number of online core and with same number of running task.

[Environment of power estimation]
- cpufreq governor used performance mode to estimate power-consumption on each frequency step.
- Use infinite-loop test program which execute while statement infinitely.
- Always measure the power consumption under same temperature during 1 minutes.
- Unit is mA.
------------------------------------------------------------------------------------------------------------------------------------
A number of Online core | Core 1 | Core 2 | Core 3 | Core 4
A number of nr_running | 0 1 | 0 1 2 | 0 1 2 3 | 0 1 2 3 4
------------------------------------------------------------------------------------------------------------------------------------
CPU Frequency |
800 MHz | 293 330 | 295 338 379 | 300 339 386 433 | 303 341 390 412 482
1000 MHz | 312 371 | 316 377 435 | 318 383 454 522 | 322 391 462 526 596
1200 MHz | 323 404 | 328 418 504 | 336 423 521 615 | 343 433 499 639 748
1600 MHz | 380 525 | 388 556 771 | 399 575 771 1011 | 412 597 822 1172 1684
------------------------------------------------------------------------------------------------------------------------------------

For example,
The case A/B/C have the same condition except for a number of online core.
- case A: Online core is 2, 1000MHz and nr_running is 1 : 377mA
- case B: Online core is 3, 1000MHz and nr_running is 1 : 383mA
- case C: Online core is 4, 1000Mz and nr_running is 1 : 391mA

If system has only one running task, cpu hotplug policy, by monitoring
cpu state through 'load_table' sysfs file on user-space,
will determine 'case A' state for reducing power-consumption.

Show the result of reading 'load_table sysfs file as following:
- cpufreq governor is ondemand_org governor.

$ cat /sys/devices/system/cpu/cpu0/cpufreq/stats/load_table
Time Frequency cpu0 cpu1 cpu2 cpu3
1300500043122 1600000 32 6 0 26
1300600079080 800000 63 10 2 45
1300700065288 800000 51 9 1 42
1300800228747 800000 51 9 1 43
1300900182997 800000 78 11 3 47
1301000106163 800000 96 26 6 48
1301100056247 1600000 45 7 1 27
1301200071373 1000000 55 9 1 37
1301300096082 800000 54 10 0 45
1301400132832 800000 70 11 2 46
1301500082290 800000 61 11 1 43
1301600236415 800000 61 9 2 43
1301700071498 800000 59 10 2 43
1301800159290 800000 55 9 1 42
1301900076332 800000 66 10 2 43
1302000102165 800000 47 9 0 43
1302100086623 800000 75 11 2 50
1302200101082 800000 66 10 4 46
1302300108873 800000 53 10 1 44
1302400373373 600000 63 12 1 54

Please let me know some opinion about this patch.

Best regards and Thanks,
Chanwoo Choi

---
drivers/cpufreq/cpufreq.c | 4 +++
drivers/cpufreq/cpufreq_governor.c | 21 ++++++++++--
drivers/cpufreq/cpufreq_stats.c | 70 ++++++++++++++++++++++++++++++++++++++
include/linux/cpufreq.h | 6 ++++
4 files changed, 99 insertions(+), 2 deletions(-)

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 5af40ad..bc50624 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -23,12 +23,17 @@
#include <linux/kernel_stat.h>
#include <linux/mutex.h>
#include <linux/slab.h>
+#include <linux/sched.h>
#include <linux/tick.h>
#include <linux/types.h>
#include <linux/workqueue.h>

#include "cpufreq_governor.h"

+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ struct cpufreq_freqs freqs;
+#endif
+
static struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy)
{
if (have_governor_per_policy())
@@ -143,11 +148,17 @@ 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
+ freqs.load[j] = 0;
+#endif
continue;
+ }

load = 100 * (wall_time - idle_time) / wall_time;
-
+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ freqs.load[j] = load;
+#endif
if (dbs_data->cdata->governor == GOV_ONDEMAND) {
int freq_avg = __cpufreq_driver_getavg(policy, j);
if (freq_avg <= 0)
@@ -160,6 +171,12 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
max_load = load;
}

+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ freqs.time = ktime_to_ns(ktime_get());
+ freqs.old = freqs.new = policy->cur;
+
+ cpufreq_notify_transition(policy, &freqs, 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..2379b1d 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -22,6 +22,8 @@
#include <linux/notifier.h>
#include <asm/cputime.h>

+#define CPUFREQ_LOAD_TABLE_MAX 20
+
static spinlock_t cpufreq_stats_lock;

struct cpufreq_stats {
@@ -35,6 +37,10 @@ struct cpufreq_stats {
unsigned int *freq_table;
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
unsigned int *trans_table;
+
+ struct cpufreq_freqs *load_table;
+ unsigned int load_last_index;
+ unsigned int load_max_index;
#endif
};

@@ -131,6 +137,38 @@ static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
return len;
}
cpufreq_freq_attr_ro(trans_table);
+
+static ssize_t show_load_table(struct cpufreq_policy *policy, char *buf)
+{
+ struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
+ struct cpufreq_freqs *load_table = stat->load_table;
+ ssize_t len = 0;
+ int i;
+ int j;
+
+ len += sprintf(buf + len, "%11s %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, "%lld %9d",
+ 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);
+
+ return len;
+}
+cpufreq_freq_attr_ro(load_table);
#endif

cpufreq_freq_attr_ro(total_trans);
@@ -141,6 +179,7 @@ static struct attribute *default_attrs[] = {
&time_in_state.attr,
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
&trans_table.attr,
+ &load_table.attr,
#endif
NULL
};
@@ -167,6 +206,9 @@ 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;
@@ -244,6 +286,16 @@ static int cpufreq_stats_create_table(struct cpufreq_policy *policy,

#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
stat->trans_table = stat->freq_table + count;
+
+ stat->load_max_index = CPUFREQ_LOAD_TABLE_MAX;
+ stat->load_last_index = 0;
+
+ alloc_size = sizeof(struct cpufreq_freqs) * stat->load_max_index;
+ stat->load_table = kzalloc(alloc_size, GFP_KERNEL);
+ if (!stat->load_table) {
+ ret = -ENOMEM;
+ goto error_out;
+ }
#endif
j = 0;
for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
@@ -312,13 +364,31 @@ static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
struct cpufreq_stats *stat;
int old_index, new_index;

+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ if (val != CPUFREQ_POSTCHANGE && val != CPUFREQ_LOADCHECK)
+#else
if (val != CPUFREQ_POSTCHANGE)
+#endif
return 0;

stat = per_cpu(cpufreq_stats_table, freq->cpu);
if (!stat)
return 0;

+#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
+ if (val == CPUFREQ_LOADCHECK) {
+ struct cpufreq_freqs *dest_freq;
+
+ dest_freq = &stat->load_table[stat->load_last_index];
+ memcpy(dest_freq, freq, sizeof(struct cpufreq_freqs));
+
+ if (++stat->load_last_index == stat->load_max_index)
+ stat->load_last_index = 0;
+
+ return 0;
+ }
+#endif
+
old_index = stat->last_index;
new_index = freq_table_get_index(stat, freq->new);

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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/