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SubjectRe: [PATCH 2/2] PM / devfreq: Add devfreq_transitions debugfs file
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Hello Chanwoo,

07.01.2020 12:05, Chanwoo Choi пишет:
> 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;

This could be:

static DEFINE_SPINLOCK(devfreq_debugfs_lock);

and then spin_lock_init() isn't needed.


Also, The "<linux/spinlock.h>" should be included directly by devfreq.c

> +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);

What about EXPORT_SYMBOL_GPL()?

> /**
> * 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);

The 'extern' attribute isn't needed for function prototypes defined in
header files.

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