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Subject[PATCH 2/2] PM / devfreq: Add devfreq_transitions debugfs file
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Add new devfreq_transitions debugfs file to track the frequency transitions
of all devfreq devices for the simple profiling as following:
- /sys/kernel/debug/devfreq/devfreq_transitions

And the user can decide the storage size (CONFIG_NR_DEVFREQ_TRANSITIONS)
in Kconfig in order to save the transition history.

[Detailed description of each field of 'devfreq_transitions' debugfs file]
- time_ms : Change time of frequency transition. (unit: millisecond)
- dev_name : Device name of h/w.
- dev : Device name made by devfreq core.
- parent_dev : If devfreq device uses the passive governor,
show parent devfreq device name.
- load_% : If devfreq device uses the simple_ondemand governor,
load is used by governor whene deciding the new frequency.
(unit: percentage)
- old_freq_hz : Frequency before changing. (unit: hz)
- new_freq_hz : Frequency after changed. (unit: hz)

[For example on Exynos5422-based Odroid-XU3 board]
$ cat /sys/kernel/debug/devfreq/devfreq_transitions
time_ms dev_name dev parent_dev load_% old_freq_hz new_freq_hz
---------- ------------------------------ ---------- ---------- ---------- ------------ ------------
14600 soc:bus_noc devfreq2 devfreq1 0 100000000 67000000
14600 soc:bus_fsys_apb devfreq3 devfreq1 0 200000000 100000000
14600 soc:bus_fsys devfreq4 devfreq1 0 200000000 100000000
14600 soc:bus_fsys2 devfreq5 devfreq1 0 150000000 75000000
14602 soc:bus_mfc devfreq6 devfreq1 0 222000000 96000000
14602 soc:bus_gen devfreq7 devfreq1 0 267000000 89000000
14602 soc:bus_g2d devfreq9 devfreq1 0 300000000 84000000
14602 soc:bus_g2d_acp devfreq10 devfreq1 0 267000000 67000000
14602 soc:bus_jpeg devfreq11 devfreq1 0 300000000 75000000
14602 soc:bus_jpeg_apb devfreq12 devfreq1 0 167000000 84000000
14603 soc:bus_disp1_fimd devfreq13 devfreq1 0 200000000 120000000
14603 soc:bus_disp1 devfreq14 devfreq1 0 300000000 120000000
14606 soc:bus_gscl_scaler devfreq15 devfreq1 0 300000000 150000000
14606 soc:bus_mscl devfreq16 devfreq1 0 333000000 84000000
14608 soc:bus_wcore devfreq1 9 333000000 84000000
14783 10c20000.memory-controller devfreq0 35 825000000 633000000
15873 soc:bus_wcore devfreq1 41 84000000 400000000
15873 soc:bus_noc devfreq2 devfreq1 0 67000000 100000000
[snip]

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
---
drivers/devfreq/Kconfig | 13 +++
drivers/devfreq/devfreq.c | 126 +++++++++++++++++++++++++++++
drivers/devfreq/governor.h | 3 +
drivers/devfreq/governor_passive.c | 2 +
include/linux/devfreq.h | 1 +
5 files changed, 145 insertions(+)

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index 0b1df12e0f21..84936eec0ef9 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -74,6 +74,19 @@ config DEVFREQ_GOV_PASSIVE
through sysfs entries. The passive governor recommends that
devfreq device uses the OPP table to get the frequency/voltage.

+comment "DEVFREQ Debugging"
+
+config NR_DEVFREQ_TRANSITIONS
+ int "Maximum storage size to save DEVFREQ Transitions (10-1000)"
+ depends on DEBUG_FS
+ range 10 1000
+ default "100"
+ help
+ Show the frequency transitions of all devfreq devices via
+ '/sys/kernel/debug/devfreq/devfreq_transitions' for the simple
+ profiling. It needs to decide the storage size to save transition
+ history of all devfreq devices.
+
comment "DEVFREQ Drivers"

config ARM_EXYNOS_BUS_DEVFREQ
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index c7f5e4e06420..7abaae06fa65 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -268,6 +268,57 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
}
EXPORT_SYMBOL(devfreq_update_status);

+/**
+ * devfreq_update_transitions() - Update frequency transitions for debugfs file
+ * @devfreq: the devfreq instance
+ * @old_freq: the previous frequency before changing the frequency
+ * @new_freq: the new frequency after frequency is changed
+ */
+struct devfreq_transitions {
+ struct devfreq *devfreq;
+ struct devfreq_freqs freqs;
+ unsigned long load;
+} debugfs_transitions[CONFIG_NR_DEVFREQ_TRANSITIONS];
+
+static spinlock_t devfreq_debugfs_lock;
+static int debugfs_transitions_index;
+
+void devfreq_update_transitions(struct devfreq *devfreq,
+ unsigned long old_freq, unsigned long new_freq,
+ unsigned long busy_time, unsigned long total_time)
+{
+ unsigned long load;
+ int i;
+
+ if (!devfreq_debugfs || !devfreq || (old_freq == new_freq))
+ return;
+
+ spin_lock_nested(&devfreq_debugfs_lock, SINGLE_DEPTH_NESTING);
+
+ i = debugfs_transitions_index;
+
+ /*
+ * Calculate the load and if load is larger than 100,
+ * initialize to 100 because the unit of load is percentage.
+ */
+ load = (total_time == 0 ? 0 : (100 * busy_time) / total_time);
+ if (load > 100)
+ load = 100;
+
+ debugfs_transitions[i].devfreq = devfreq;
+ debugfs_transitions[i].freqs.time = ktime_to_ms(ktime_get());
+ debugfs_transitions[i].freqs.old = old_freq;
+ debugfs_transitions[i].freqs.new = new_freq;
+ debugfs_transitions[i].load = load;
+
+ if (++i == CONFIG_NR_DEVFREQ_TRANSITIONS)
+ i = 0;
+ debugfs_transitions_index = i;
+
+ spin_unlock(&devfreq_debugfs_lock);
+}
+EXPORT_SYMBOL(devfreq_update_transitions);
+
/**
* find_devfreq_governor() - Find devfreq governor from name
* @name: name of the governor
@@ -401,6 +452,10 @@ static int set_target(struct devfreq *devfreq,
return err;
}

+ devfreq_update_transitions(devfreq, cur_freq, new_freq,
+ devfreq->last_status.busy_time,
+ devfreq->last_status.total_time);
+
freqs.new = new_freq;
notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);

@@ -1787,6 +1842,72 @@ static int devfreq_summary_show(struct seq_file *s, void *data)
}
DEFINE_SHOW_ATTRIBUTE(devfreq_summary);

+/**
+ * devfreq_transitions_show() - Show the frequency transitions of the registered
+ * devfreq devices via 'devfreq_transitions' debugfs file.
+ */
+static int devfreq_transitions_show(struct seq_file *s, void *data)
+{
+ struct devfreq *devfreq = NULL;
+ struct devfreq *p_devfreq = NULL;
+ struct devfreq_freqs *freqs = NULL;
+ unsigned long load;
+ int i = debugfs_transitions_index;
+ int count;
+
+ seq_printf(s, "%-10s %-30s %-10s %-10s %-6s %-12s %-12s\n",
+ "time_ms",
+ "dev_name",
+ "dev",
+ "parent_dev",
+ "load_%",
+ "old_freq_hz",
+ "new_freq_hz");
+ seq_printf(s, "%-10s %-30s %-10s %-10s %-6s %-12s %-12s\n",
+ "----------",
+ "------------------------------",
+ "----------",
+ "----------",
+ "----------",
+ "------------",
+ "------------");
+
+ spin_lock(&devfreq_debugfs_lock);
+ for (count = 0; count < CONFIG_NR_DEVFREQ_TRANSITIONS; count++) {
+ devfreq = debugfs_transitions[i].devfreq;
+ freqs = &debugfs_transitions[i].freqs;
+ load = debugfs_transitions[i].load;
+
+ i = (CONFIG_NR_DEVFREQ_TRANSITIONS == ++i) ? 0 : i;
+ if (!devfreq)
+ continue;
+
+#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
+ if (!strncmp(devfreq->governor_name,
+ DEVFREQ_GOV_PASSIVE, DEVFREQ_NAME_LEN)) {
+ struct devfreq_passive_data *data = devfreq->data;
+
+ if (data)
+ p_devfreq = data->parent;
+ } else {
+ p_devfreq = NULL;
+ }
+#endif
+ seq_printf(s, "%-10lld %-30s %-10s %-10s %-6ld %-12ld %-12ld\n",
+ freqs->time,
+ dev_name(devfreq->dev.parent),
+ dev_name(&devfreq->dev),
+ p_devfreq ? dev_name(&p_devfreq->dev) : "",
+ load,
+ freqs->old,
+ freqs->new);
+ }
+ spin_unlock(&devfreq_debugfs_lock);
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(devfreq_transitions);
+
static int __init devfreq_init(void)
{
devfreq_class = class_create(THIS_MODULE, "devfreq");
@@ -1808,9 +1929,14 @@ static int __init devfreq_init(void)
devfreq_debugfs = NULL;
pr_warn("%s: couldn't create debugfs dir\n", __FILE__);
} else {
+ spin_lock_init(&devfreq_debugfs_lock);
+
debugfs_create_file("devfreq_summary", 0444,
devfreq_debugfs, NULL,
&devfreq_summary_fops);
+ debugfs_create_file("devfreq_transitions", 0444,
+ devfreq_debugfs, NULL,
+ &devfreq_transitions_fops);
}

return 0;
diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
index dc7533ccc3db..01eecfdaf2d6 100644
--- a/drivers/devfreq/governor.h
+++ b/drivers/devfreq/governor.h
@@ -68,6 +68,9 @@ extern int devfreq_add_governor(struct devfreq_governor *governor);
extern int devfreq_remove_governor(struct devfreq_governor *governor);

extern int devfreq_update_status(struct devfreq *devfreq, unsigned long freq);
+extern void devfreq_update_transitions(struct devfreq *devfreq,
+ unsigned long old_freq, unsigned long new_freq,
+ unsigned long busy_time, unsigned long total_time);

static inline int devfreq_update_stats(struct devfreq *df)
{
diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
index be6eeab9c814..05fa654239f5 100644
--- a/drivers/devfreq/governor_passive.c
+++ b/drivers/devfreq/governor_passive.c
@@ -109,6 +109,8 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
if (ret < 0)
goto out;

+ devfreq_update_transitions(devfreq, devfreq->previous_freq, freq, 0, 0);
+
if (devfreq->profile->freq_table
&& (devfreq_update_status(devfreq, freq)))
dev_err(&devfreq->dev,
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 49cdb2378030..933692e5d867 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -196,6 +196,7 @@ struct devfreq {
};

struct devfreq_freqs {
+ s64 time;
unsigned long old;
unsigned long new;
};
--
2.17.1
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