* [RFC RESEND 1/3] PM / devfreq: Add watermark events
2014-12-05 13:41 [RFC RESEND 0/3] Add watermark support to devfreq Arto Merilainen
@ 2014-12-05 13:41 ` Arto Merilainen
2014-12-09 7:17 ` Alexandre Courbot
2014-12-05 13:41 ` [RFC RESEND 2/3] PM / devfreq: Add watermark simple governor Arto Merilainen
` (2 subsequent siblings)
3 siblings, 1 reply; 7+ messages in thread
From: Arto Merilainen @ 2014-12-05 13:41 UTC (permalink / raw)
To: myungjoo.ham, kyungmin.park, tomeu.vizoso, gnurou
Cc: javier.martinez, linux-pm, linux-kernel, linux-tegra, swarren,
thierry.reding, grant.likely, srasal, amerilainen
From: Shridhar Rasal <srasal@nvidia.com>
This patch adds support for watermark events. These events inform
the governor that the device load has gone below (low watermark) or
above (high watermark) certain load value.
Signed-off-by: Shridhar Rasal <srasal@nvidia.com>
Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
---
drivers/devfreq/devfreq.c | 19 +++++++++++++++++++
drivers/devfreq/governor.h | 1 +
include/linux/devfreq.h | 26 ++++++++++++++++++++++++++
3 files changed, 46 insertions(+)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 30b538d8cc90..8333d024132a 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -1050,6 +1050,25 @@ static struct attribute *devfreq_attrs[] = {
};
ATTRIBUTE_GROUPS(devfreq);
+/**
+ * devfreq_watermark_event() - Handles watermark events
+ * @devfreq: the devfreq instance to be updated
+ * @type: type of watermark event
+ */
+int devfreq_watermark_event(struct devfreq *devfreq, int type)
+{
+ if (!devfreq)
+ return -EINVAL;
+
+ if (!devfreq->governor)
+ return -EINVAL;
+
+ return devfreq->governor->event_handler(devfreq,
+ DEVFREQ_GOV_WMARK, &type);
+}
+EXPORT_SYMBOL(devfreq_watermark_event);
+
+
static int __init devfreq_init(void)
{
devfreq_class = class_create(THIS_MODULE, "devfreq");
diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
index fad7d6321978..fb9875388f3f 100644
--- a/drivers/devfreq/governor.h
+++ b/drivers/devfreq/governor.h
@@ -24,6 +24,7 @@
#define DEVFREQ_GOV_INTERVAL 0x3
#define DEVFREQ_GOV_SUSPEND 0x4
#define DEVFREQ_GOV_RESUME 0x5
+#define DEVFREQ_GOV_WMARK 0x6
/* Caution: devfreq->lock must be locked before calling update_devfreq */
extern int update_devfreq(struct devfreq *devfreq);
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index f1863dcd83ea..b5bf6c4fe286 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -21,6 +21,12 @@
struct devfreq;
+enum watermark_type {
+ NO_WATERMARK_EVENT = 0,
+ HIGH_WATERMARK_EVENT = 1,
+ LOW_WATERMARK_EVENT = 2
+};
+
/**
* struct devfreq_dev_status - Data given from devfreq user device to
* governors. Represents the performance
@@ -68,6 +74,16 @@ struct devfreq_dev_status {
* status to devfreq, which is used by governors.
* @get_cur_freq: The device should provide the current frequency
* at which it is operating.
+ * @set_high_wmark: This is an optional callback to set high
+ * watermark for watermark event. The value is
+ * be scaled between 0 and 1000 where 1000 equals to
+ * 100% load. Setting this value to 1000 disables
+ * the event
+ * @set_low_wmark: This is an optional callback to set low
+ * watermark for watermark event. The value is
+ * be scaled between 0 and 1000 where 1000 equals to
+ * 100% load. Setting this value to 0 disables the
+ * event.
* @exit: An optional callback that is called when devfreq
* is removing the devfreq object due to error or
* from devfreq_remove_device() call. If the user
@@ -84,6 +100,8 @@ struct devfreq_dev_profile {
int (*get_dev_status)(struct device *dev,
struct devfreq_dev_status *stat);
int (*get_cur_freq)(struct device *dev, unsigned long *freq);
+ int (*set_high_wmark)(struct device *dev, unsigned int val);
+ int (*set_low_wmark)(struct device *dev, unsigned int val);
void (*exit)(struct device *dev);
unsigned int *freq_table;
@@ -191,6 +209,8 @@ extern void devm_devfreq_remove_device(struct device *dev,
/* Supposed to be called by PM_SLEEP/PM_RUNTIME callbacks */
extern int devfreq_suspend_device(struct devfreq *devfreq);
extern int devfreq_resume_device(struct devfreq *devfreq);
+extern int devfreq_watermark_event(struct devfreq *devfreq,
+ int type);
/* Helper functions for devfreq user device driver with OPP. */
extern struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
@@ -289,6 +309,12 @@ static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
struct devfreq *devfreq)
{
}
+
+static inline int devfreq_watermark_event(struct devfreq *devfreq,
+ int type)
+{
+ return 0;
+}
#endif /* CONFIG_PM_DEVFREQ */
#endif /* __LINUX_DEVFREQ_H__ */
--
1.8.1.5
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [RFC RESEND 1/3] PM / devfreq: Add watermark events
2014-12-05 13:41 ` [RFC RESEND 1/3] PM / devfreq: Add watermark events Arto Merilainen
@ 2014-12-09 7:17 ` Alexandre Courbot
0 siblings, 0 replies; 7+ messages in thread
From: Alexandre Courbot @ 2014-12-09 7:17 UTC (permalink / raw)
To: Arto Merilainen
Cc: MyungJoo Ham, Kyungmin Park, Tomeu Vizoso,
Javier Martinez Canillas, linux-pm, Linux Kernel Mailing List,
linux-tegra, Stephen Warren, Thierry Reding, Grant Likely,
srasal
On Fri, Dec 5, 2014 at 10:41 PM, Arto Merilainen <amerilainen@nvidia.com> wrote:
> From: Shridhar Rasal <srasal@nvidia.com>
>
> This patch adds support for watermark events. These events inform
> the governor that the device load has gone below (low watermark) or
> above (high watermark) certain load value.
This is definitely a useful feature to have, as it reflects what
efficient hardware does (raise an interrupt when load goes above/under
a certain threshold). In particular Tomeu's ACTMON driver would
probably greatly benefit from it.
A few comments below:
>
> Signed-off-by: Shridhar Rasal <srasal@nvidia.com>
> Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
> ---
> drivers/devfreq/devfreq.c | 19 +++++++++++++++++++
> drivers/devfreq/governor.h | 1 +
> include/linux/devfreq.h | 26 ++++++++++++++++++++++++++
> 3 files changed, 46 insertions(+)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 30b538d8cc90..8333d024132a 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -1050,6 +1050,25 @@ static struct attribute *devfreq_attrs[] = {
> };
> ATTRIBUTE_GROUPS(devfreq);
>
> +/**
> + * devfreq_watermark_event() - Handles watermark events
> + * @devfreq: the devfreq instance to be updated
> + * @type: type of watermark event
> + */
> +int devfreq_watermark_event(struct devfreq *devfreq, int type)
Here I suppose "type" is to be an enum watermark_type - therefore it
should probably be changed to that type instead of int.
> +{
> + if (!devfreq)
> + return -EINVAL;
> +
> + if (!devfreq->governor)
> + return -EINVAL;
Let's fold these two conditions into "if (!devfreq || !devfreq->governor)"
> +
> + return devfreq->governor->event_handler(devfreq,
> + DEVFREQ_GOV_WMARK, &type);
> +}
> +EXPORT_SYMBOL(devfreq_watermark_event);
> +
> +
Extra whiteline here.
> static int __init devfreq_init(void)
> {
> devfreq_class = class_create(THIS_MODULE, "devfreq");
> diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
> index fad7d6321978..fb9875388f3f 100644
> --- a/drivers/devfreq/governor.h
> +++ b/drivers/devfreq/governor.h
> @@ -24,6 +24,7 @@
> #define DEVFREQ_GOV_INTERVAL 0x3
> #define DEVFREQ_GOV_SUSPEND 0x4
> #define DEVFREQ_GOV_RESUME 0x5
> +#define DEVFREQ_GOV_WMARK 0x6
>
> /* Caution: devfreq->lock must be locked before calling update_devfreq */
> extern int update_devfreq(struct devfreq *devfreq);
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index f1863dcd83ea..b5bf6c4fe286 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -21,6 +21,12 @@
>
> struct devfreq;
>
> +enum watermark_type {
Change the name to devfreq_watermark_event maybe? We know it's a type
already from the context, and we should use the devfreq_ prefix to
avoid name collisions.
> + NO_WATERMARK_EVENT = 0,
> + HIGH_WATERMARK_EVENT = 1,
> + LOW_WATERMARK_EVENT = 2
... and if the type is renamed to watermark_event, these could become
DEVFREQ_NO_WATERMARK, DEVFREQ_HIGH_WATERMARK, and
DEVFREQ_LOW_WATERMARK.
> +};
> +
> /**
> * struct devfreq_dev_status - Data given from devfreq user device to
> * governors. Represents the performance
> @@ -68,6 +74,16 @@ struct devfreq_dev_status {
> * status to devfreq, which is used by governors.
> * @get_cur_freq: The device should provide the current frequency
> * at which it is operating.
> + * @set_high_wmark: This is an optional callback to set high
> + * watermark for watermark event. The value is
> + * be scaled between 0 and 1000 where 1000 equals to
> + * 100% load. Setting this value to 1000 disables
> + * the event
> + * @set_low_wmark: This is an optional callback to set low
> + * watermark for watermark event. The value is
> + * be scaled between 0 and 1000 where 1000 equals to
> + * 100% load. Setting this value to 0 disables the
> + * event.
>From the comment it is not clear whether the 0..1000 range corresponds
to the load between two frequencies in the frequencies table, or
covers the whole frequency table. I understand it is the former, but
it would be nice to explicitly state it.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [RFC RESEND 2/3] PM / devfreq: Add watermark simple governor
2014-12-05 13:41 [RFC RESEND 0/3] Add watermark support to devfreq Arto Merilainen
2014-12-05 13:41 ` [RFC RESEND 1/3] PM / devfreq: Add watermark events Arto Merilainen
@ 2014-12-05 13:41 ` Arto Merilainen
2014-12-09 7:18 ` Alexandre Courbot
2014-12-05 13:41 ` [RFC RESEND 3/3] PM / devfreq: Add watermark active governor Arto Merilainen
2014-12-09 13:25 ` [RFC RESEND 0/3] Add watermark support to devfreq Tomeu Vizoso
3 siblings, 1 reply; 7+ messages in thread
From: Arto Merilainen @ 2014-12-05 13:41 UTC (permalink / raw)
To: myungjoo.ham, kyungmin.park, tomeu.vizoso, gnurou
Cc: javier.martinez, linux-pm, linux-kernel, linux-tegra, swarren,
thierry.reding, grant.likely, srasal, amerilainen
From: Shridhar Rasal <srasal@nvidia.com>
This patch adds a new devfreq governor, watermark simple. The
governor decides next frequency naively by selecting the previous
frequency in the frequency table if we received low watermark
- or the next frequency in case we received high watermark.
Signed-off-by: Shridhar Rasal <srasal@nvidia.com>
Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
---
drivers/devfreq/Kconfig | 7 +
drivers/devfreq/Makefile | 1 +
drivers/devfreq/governor_wmark_simple.c | 245 ++++++++++++++++++++++++++++++++
3 files changed, 253 insertions(+)
create mode 100644 drivers/devfreq/governor_wmark_simple.c
diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index faf4e70c42e0..37710d999ffe 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -63,6 +63,13 @@ config DEVFREQ_GOV_USERSPACE
Otherwise, the governor does not change the frequnecy
given at the initialization.
+config DEVFREQ_GOV_WMARK_SIMPLE
+ tristate "Simple Watermark"
+ help
+ Sets the frequency based on monitor watermark events.
+ This governor returns the next frequency from frequency table
+ based on type watermark event.
+
comment "DEVFREQ Drivers"
config ARM_EXYNOS4_BUS_DEVFREQ
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 16138c9e0d58..92024eeb73b6 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND) += governor_simpleondemand.o
obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE) += governor_performance.o
obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE) += governor_powersave.o
obj-$(CONFIG_DEVFREQ_GOV_USERSPACE) += governor_userspace.o
+obj-$(CONFIG_DEVFREQ_GOV_WMARK_SIMPLE) += governor_wmark_simple.o
# DEVFREQ Drivers
obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ) += exynos/
diff --git a/drivers/devfreq/governor_wmark_simple.c b/drivers/devfreq/governor_wmark_simple.c
new file mode 100644
index 000000000000..bd14adcc84cb
--- /dev/null
+++ b/drivers/devfreq/governor_wmark_simple.c
@@ -0,0 +1,245 @@
+/*
+ * Copyright (c) 2014, NVIDIA CORPORATION. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/devfreq.h>
+#include <linux/debugfs.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+
+#include "governor.h"
+
+struct wmark_gov_info {
+ /* probed from the devfreq */
+ unsigned int *freqlist;
+ int freq_count;
+
+ /* algorithm parameters */
+ unsigned int p_high_wmark;
+ unsigned int p_low_wmark;
+
+ /* dynamically changing data */
+ enum watermark_type event;
+ unsigned int last_request;
+
+ /* common data */
+ struct devfreq *df;
+ struct platform_device *pdev;
+ struct dentry *debugdir;
+};
+
+static unsigned long freqlist_up(struct wmark_gov_info *wmarkinfo,
+ unsigned long curr_freq)
+{
+ int i, pos;
+
+ for (i = 0; i < wmarkinfo->freq_count; i++)
+ if (wmarkinfo->freqlist[i] > curr_freq)
+ break;
+
+ pos = min(wmarkinfo->freq_count - 1, i);
+
+ return wmarkinfo->freqlist[pos];
+}
+
+static unsigned int freqlist_down(struct wmark_gov_info *wmarkinfo,
+ unsigned long curr_freq)
+{
+ int i, pos;
+
+ for (i = wmarkinfo->freq_count - 1; i >= 0; i--)
+ if (wmarkinfo->freqlist[i] < curr_freq)
+ break;
+
+ pos = max(0, i);
+ return wmarkinfo->freqlist[pos];
+}
+
+static int devfreq_watermark_target_freq(struct devfreq *df,
+ unsigned long *freq)
+{
+ struct wmark_gov_info *wmarkinfo = df->data;
+ struct devfreq_dev_status dev_stat;
+ int err;
+
+ err = df->profile->get_dev_status(df->dev.parent, &dev_stat);
+ if (err < 0)
+ return err;
+
+ switch (wmarkinfo->event) {
+ case HIGH_WATERMARK_EVENT:
+ *freq = freqlist_up(wmarkinfo, dev_stat.current_frequency);
+
+ /* always enable low watermark */
+ df->profile->set_low_wmark(df->dev.parent,
+ wmarkinfo->p_low_wmark);
+
+ /* disable high watermark if no change */
+ if (*freq == wmarkinfo->last_request)
+ df->profile->set_high_wmark(df->dev.parent, 1000);
+ break;
+ case LOW_WATERMARK_EVENT:
+ *freq = freqlist_down(wmarkinfo, dev_stat.current_frequency);
+
+ /* always enable high watermark */
+ df->profile->set_high_wmark(df->dev.parent,
+ wmarkinfo->p_high_wmark);
+
+ /* disable low watermark if no change */
+ if (*freq == wmarkinfo->last_request)
+ df->profile->set_low_wmark(df->dev.parent, 0);
+ break;
+ default:
+ break;
+ }
+
+ /* Mark that you handled event */
+ wmarkinfo->event = NO_WATERMARK_EVENT;
+ wmarkinfo->last_request = *freq;
+
+ return 0;
+}
+
+static void devfreq_watermark_debug_start(struct devfreq *df)
+{
+ struct wmark_gov_info *wmarkinfo = df->data;
+ char dirname[128];
+
+ snprintf(dirname, sizeof(dirname), "%s_scaling",
+ to_platform_device(df->dev.parent)->name);
+
+ if (!wmarkinfo)
+ return;
+
+ wmarkinfo->debugdir = debugfs_create_dir(dirname, NULL);
+ if (!wmarkinfo->debugdir)
+ return;
+
+ debugfs_create_u32("low_wmark", S_IRUGO | S_IWUSR,
+ wmarkinfo->debugdir, &wmarkinfo->p_low_wmark);
+ debugfs_create_u32("high_wmark", S_IRUGO | S_IWUSR,
+ wmarkinfo->debugdir, &wmarkinfo->p_high_wmark);
+}
+
+static void devfreq_watermark_debug_stop(struct devfreq *df)
+{
+ struct wmark_gov_info *wmarkinfo = df->data;
+
+ debugfs_remove_recursive(wmarkinfo->debugdir);
+}
+
+static int devfreq_watermark_start(struct devfreq *df)
+{
+ struct wmark_gov_info *wmarkinfo;
+ struct platform_device *pdev = to_platform_device(df->dev.parent);
+
+ if (!df->profile->freq_table) {
+ dev_err(&pdev->dev, "Frequency table missing\n");
+ return -EINVAL;
+ }
+
+ wmarkinfo = kzalloc(sizeof(struct wmark_gov_info), GFP_KERNEL);
+ if (!wmarkinfo)
+ return -ENOMEM;
+
+ df->data = (void *)wmarkinfo;
+ wmarkinfo->freqlist = df->profile->freq_table;
+ wmarkinfo->freq_count = df->profile->max_state;
+ wmarkinfo->event = NO_WATERMARK_EVENT;
+ wmarkinfo->df = df;
+ wmarkinfo->pdev = pdev;
+ wmarkinfo->p_low_wmark = 100;
+ wmarkinfo->p_high_wmark = 600;
+
+ devfreq_watermark_debug_start(df);
+
+ return 0;
+}
+
+static int devfreq_watermark_event_handler(struct devfreq *df,
+ unsigned int event,
+ void *wmark_type)
+{
+ int ret = 0;
+ struct wmark_gov_info *wmarkinfo = df->data;
+ enum watermark_type *type = wmark_type;
+
+ switch (event) {
+ case DEVFREQ_GOV_START:
+ devfreq_watermark_start(df);
+ wmarkinfo = df->data;
+ if (df->profile->set_low_wmark)
+ df->profile->set_low_wmark(df->dev.parent,
+ wmarkinfo->p_low_wmark);
+ if (df->profile->set_high_wmark)
+ df->profile->set_high_wmark(df->dev.parent,
+ wmarkinfo->p_high_wmark);
+ break;
+ case DEVFREQ_GOV_STOP:
+ devfreq_watermark_debug_stop(df);
+ break;
+ case DEVFREQ_GOV_SUSPEND:
+ devfreq_monitor_suspend(df);
+ break;
+
+ case DEVFREQ_GOV_RESUME:
+ if (df->profile->set_low_wmark)
+ df->profile->set_low_wmark(df->dev.parent,
+ wmarkinfo->p_low_wmark);
+ if (df->profile->set_high_wmark)
+ df->profile->set_high_wmark(df->dev.parent,
+ wmarkinfo->p_high_wmark);
+ devfreq_monitor_resume(df);
+ break;
+
+ case DEVFREQ_GOV_WMARK:
+ /* Set watermark interrupt type */
+ wmarkinfo->event = *type;
+
+ mutex_lock(&df->lock);
+ update_devfreq(df);
+ mutex_unlock(&df->lock);
+
+ break;
+
+ default:
+ break;
+ }
+
+ return ret;
+}
+
+static struct devfreq_governor devfreq_watermark = {
+ .name = "wmark_simple",
+ .get_target_freq = devfreq_watermark_target_freq,
+ .event_handler = devfreq_watermark_event_handler,
+};
+
+
+static int __init devfreq_watermark_init(void)
+{
+ return devfreq_add_governor(&devfreq_watermark);
+}
+
+static void __exit devfreq_watermark_exit(void)
+{
+ devfreq_remove_governor(&devfreq_watermark);
+}
+
+rootfs_initcall(devfreq_watermark_init);
+module_exit(devfreq_watermark_exit);
--
1.8.1.5
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [RFC RESEND 2/3] PM / devfreq: Add watermark simple governor
2014-12-05 13:41 ` [RFC RESEND 2/3] PM / devfreq: Add watermark simple governor Arto Merilainen
@ 2014-12-09 7:18 ` Alexandre Courbot
0 siblings, 0 replies; 7+ messages in thread
From: Alexandre Courbot @ 2014-12-09 7:18 UTC (permalink / raw)
To: Arto Merilainen
Cc: MyungJoo Ham, Kyungmin Park, Tomeu Vizoso,
Javier Martinez Canillas, linux-pm, Linux Kernel Mailing List,
linux-tegra, Stephen Warren, Thierry Reding, Grant Likely,
srasal
On Fri, Dec 5, 2014 at 10:41 PM, Arto Merilainen <amerilainen@nvidia.com> wrote:
> From: Shridhar Rasal <srasal@nvidia.com>
>
> This patch adds a new devfreq governor, watermark simple. The
> governor decides next frequency naively by selecting the previous
> frequency in the frequency table if we received low watermark
> - or the next frequency in case we received high watermark.
>
> Signed-off-by: Shridhar Rasal <srasal@nvidia.com>
> Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
> ---
> drivers/devfreq/Kconfig | 7 +
> drivers/devfreq/Makefile | 1 +
> drivers/devfreq/governor_wmark_simple.c | 245 ++++++++++++++++++++++++++++++++
> 3 files changed, 253 insertions(+)
> create mode 100644 drivers/devfreq/governor_wmark_simple.c
>
> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> index faf4e70c42e0..37710d999ffe 100644
> --- a/drivers/devfreq/Kconfig
> +++ b/drivers/devfreq/Kconfig
> @@ -63,6 +63,13 @@ config DEVFREQ_GOV_USERSPACE
> Otherwise, the governor does not change the frequnecy
> given at the initialization.
>
> +config DEVFREQ_GOV_WMARK_SIMPLE
> + tristate "Simple Watermark"
> + help
> + Sets the frequency based on monitor watermark events.
> + This governor returns the next frequency from frequency table
> + based on type watermark event.
> +
> comment "DEVFREQ Drivers"
>
> config ARM_EXYNOS4_BUS_DEVFREQ
> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
> index 16138c9e0d58..92024eeb73b6 100644
> --- a/drivers/devfreq/Makefile
> +++ b/drivers/devfreq/Makefile
> @@ -3,6 +3,7 @@ obj-$(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND) += governor_simpleondemand.o
> obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE) += governor_performance.o
> obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE) += governor_powersave.o
> obj-$(CONFIG_DEVFREQ_GOV_USERSPACE) += governor_userspace.o
> +obj-$(CONFIG_DEVFREQ_GOV_WMARK_SIMPLE) += governor_wmark_simple.o
>
> # DEVFREQ Drivers
> obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ) += exynos/
> diff --git a/drivers/devfreq/governor_wmark_simple.c b/drivers/devfreq/governor_wmark_simple.c
> new file mode 100644
> index 000000000000..bd14adcc84cb
> --- /dev/null
> +++ b/drivers/devfreq/governor_wmark_simple.c
> @@ -0,0 +1,245 @@
> +/*
> + * Copyright (c) 2014, NVIDIA CORPORATION. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/devfreq.h>
> +#include <linux/debugfs.h>
> +#include <linux/types.h>
> +#include <linux/slab.h>
> +#include <linux/device.h>
> +#include <linux/notifier.h>
> +#include <linux/platform_device.h>
> +
> +#include "governor.h"
> +
> +struct wmark_gov_info {
> + /* probed from the devfreq */
> + unsigned int *freqlist;
> + int freq_count;
> +
> + /* algorithm parameters */
> + unsigned int p_high_wmark;
> + unsigned int p_low_wmark;
> +
> + /* dynamically changing data */
> + enum watermark_type event;
I would rename this to last_event for clarity.
> + unsigned int last_request;
last_freq might be a more appropriate name here.
> +
> + /* common data */
> + struct devfreq *df;
Unless I missed something this member is only set once in
devfreq_watermark_start() and never touched afterwards.
> + struct platform_device *pdev;
Same with this one.
> + struct dentry *debugdir;
> +};
> +
> +static unsigned long freqlist_up(struct wmark_gov_info *wmarkinfo,
> + unsigned long curr_freq)
> +{
> + int i, pos;
> +
> + for (i = 0; i < wmarkinfo->freq_count; i++)
> + if (wmarkinfo->freqlist[i] > curr_freq)
> + break;
> +
> + pos = min(wmarkinfo->freq_count - 1, i);
> +
> + return wmarkinfo->freqlist[pos];
> +}
> +
> +static unsigned int freqlist_down(struct wmark_gov_info *wmarkinfo,
> + unsigned long curr_freq)
> +{
> + int i, pos;
> +
> + for (i = wmarkinfo->freq_count - 1; i >= 0; i--)
> + if (wmarkinfo->freqlist[i] < curr_freq)
> + break;
> +
> + pos = max(0, i);
> + return wmarkinfo->freqlist[pos];
> +}
> +
> +static int devfreq_watermark_target_freq(struct devfreq *df,
> + unsigned long *freq)
> +{
> + struct wmark_gov_info *wmarkinfo = df->data;
> + struct devfreq_dev_status dev_stat;
> + int err;
> +
> + err = df->profile->get_dev_status(df->dev.parent, &dev_stat);
> + if (err < 0)
> + return err;
> +
> + switch (wmarkinfo->event) {
> + case HIGH_WATERMARK_EVENT:
> + *freq = freqlist_up(wmarkinfo, dev_stat.current_frequency);
> +
> + /* always enable low watermark */
> + df->profile->set_low_wmark(df->dev.parent,
> + wmarkinfo->p_low_wmark);
> +
> + /* disable high watermark if no change */
> + if (*freq == wmarkinfo->last_request)
> + df->profile->set_high_wmark(df->dev.parent, 1000);
> + break;
> + case LOW_WATERMARK_EVENT:
> + *freq = freqlist_down(wmarkinfo, dev_stat.current_frequency);
> +
> + /* always enable high watermark */
> + df->profile->set_high_wmark(df->dev.parent,
> + wmarkinfo->p_high_wmark);
> +
> + /* disable low watermark if no change */
> + if (*freq == wmarkinfo->last_request)
> + df->profile->set_low_wmark(df->dev.parent, 0);
> + break;
> + default:
> + break;
> + }
> +
> + /* Mark that you handled event */
s/you/we
> + wmarkinfo->event = NO_WATERMARK_EVENT;
> + wmarkinfo->last_request = *freq;
> +
> + return 0;
> +}
> +
> +static void devfreq_watermark_debug_start(struct devfreq *df)
> +{
> + struct wmark_gov_info *wmarkinfo = df->data;
> + char dirname[128];
> +
> + snprintf(dirname, sizeof(dirname), "%s_scaling",
> + to_platform_device(df->dev.parent)->name);
> +
> + if (!wmarkinfo)
> + return;
> +
> + wmarkinfo->debugdir = debugfs_create_dir(dirname, NULL);
> + if (!wmarkinfo->debugdir)
> + return;
> +
> + debugfs_create_u32("low_wmark", S_IRUGO | S_IWUSR,
> + wmarkinfo->debugdir, &wmarkinfo->p_low_wmark);
> + debugfs_create_u32("high_wmark", S_IRUGO | S_IWUSR,
> + wmarkinfo->debugdir, &wmarkinfo->p_high_wmark);
Shouldn't we call set_low_wmark() and set_high_wmark() when these
values are changed so the hardware reacts to the new values?
> +}
> +
> +static void devfreq_watermark_debug_stop(struct devfreq *df)
> +{
> + struct wmark_gov_info *wmarkinfo = df->data;
> +
> + debugfs_remove_recursive(wmarkinfo->debugdir);
> +}
> +
> +static int devfreq_watermark_start(struct devfreq *df)
> +{
> + struct wmark_gov_info *wmarkinfo;
> + struct platform_device *pdev = to_platform_device(df->dev.parent);
> +
> + if (!df->profile->freq_table) {
> + dev_err(&pdev->dev, "Frequency table missing\n");
> + return -EINVAL;
This error is not propagated by devfreq_watermark_event_handler(). It
definitely should be.
Also you will want to fail if d->profile->max_state == 0, otherwise
funny things will happen when a watermark is reached.
> + }
> +
> + wmarkinfo = kzalloc(sizeof(struct wmark_gov_info), GFP_KERNEL);
This memory is never freed.
> + if (!wmarkinfo)
> + return -ENOMEM;
> +
> + df->data = (void *)wmarkinfo;
> + wmarkinfo->freqlist = df->profile->freq_table;
> + wmarkinfo->freq_count = df->profile->max_state;
Contrary to what its comment says, freq_table is not optional anymore
and only used for statistics if one intents to use a watermark
governor. It should probably be updated to reflect this.
> + wmarkinfo->event = NO_WATERMARK_EVENT;
> + wmarkinfo->df = df;
> + wmarkinfo->pdev = pdev;
> + wmarkinfo->p_low_wmark = 100;
> + wmarkinfo->p_high_wmark = 600;
> +
> + devfreq_watermark_debug_start(df);
> +
> + return 0;
> +}
> +
> +static int devfreq_watermark_event_handler(struct devfreq *df,
> + unsigned int event,
> + void *wmark_type)
> +{
> + int ret = 0;
> + struct wmark_gov_info *wmarkinfo = df->data;
> + enum watermark_type *type = wmark_type;
> +
> + switch (event) {
> + case DEVFREQ_GOV_START:
> + devfreq_watermark_start(df);
This function does not really start anything - it prepares df to be
used with this governor. Maybe call it devfreq_watermark_init()
instead? Then you could have a devfreq_watermark_fini() function
called when we stop the governor that frees the memory previously
allocated.
Also I think you want to call try_module_get(THIS_MODULE) here to
prevent the governor module from being removed it if is used by
someone.
> + wmarkinfo = df->data;
> + if (df->profile->set_low_wmark)
> + df->profile->set_low_wmark(df->dev.parent,
> + wmarkinfo->p_low_wmark);
> + if (df->profile->set_high_wmark)
> + df->profile->set_high_wmark(df->dev.parent,
> + wmarkinfo->p_high_wmark);
Isn't it an error if one (or both) of these functions is missing? For
we will never receive any event. Not sure about this.
> + break;
> + case DEVFREQ_GOV_STOP:
> + devfreq_watermark_debug_stop(df);
As said above, have a devfreq_watermark_fini() (or any other name)
here that frees the kzalloc'd memory and calls
devfreq_watermark_debug_stop(). Also you should probably call
module_put(THIS_MODULE).
> + break;
> + case DEVFREQ_GOV_SUSPEND:
> + devfreq_monitor_suspend(df);
Shouldn't we call set_low_wmark() and set_high_wmark() to prevent the
hardware from firing interrupts after devfreq_monitor_suspend() is
called?
^ permalink raw reply [flat|nested] 7+ messages in thread
* [RFC RESEND 3/3] PM / devfreq: Add watermark active governor
2014-12-05 13:41 [RFC RESEND 0/3] Add watermark support to devfreq Arto Merilainen
2014-12-05 13:41 ` [RFC RESEND 1/3] PM / devfreq: Add watermark events Arto Merilainen
2014-12-05 13:41 ` [RFC RESEND 2/3] PM / devfreq: Add watermark simple governor Arto Merilainen
@ 2014-12-05 13:41 ` Arto Merilainen
2014-12-09 13:25 ` [RFC RESEND 0/3] Add watermark support to devfreq Tomeu Vizoso
3 siblings, 0 replies; 7+ messages in thread
From: Arto Merilainen @ 2014-12-05 13:41 UTC (permalink / raw)
To: myungjoo.ham, kyungmin.park, tomeu.vizoso, gnurou
Cc: javier.martinez, linux-pm, linux-kernel, linux-tegra, swarren,
thierry.reding, grant.likely, srasal, amerilainen
This patch adds a new watermark governor that actively alters the
watermark values based on the current frequency and target load.
The governor takes target load as a given property (80% by default)
and every time when the governor re-estimation is triggered, the
governor checks the current load and calculates the next frequency
that would push the device as close this target load as possible.
At this point also the watermark values are updated so that next
time the interrupt should come when the load change is significant
enough to cause frequency change to either next or previous
frequency.
Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
---
drivers/devfreq/Kconfig | 11 ++
drivers/devfreq/Makefile | 1 +
drivers/devfreq/governor_wmark_active.c | 276 ++++++++++++++++++++++++++++++++
3 files changed, 288 insertions(+)
create mode 100644 drivers/devfreq/governor_wmark_active.c
diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index 37710d999ffe..dc5b207e9c3b 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -70,6 +70,17 @@ config DEVFREQ_GOV_WMARK_SIMPLE
This governor returns the next frequency from frequency table
based on type watermark event.
+config DEVFREQ_GOV_WMARK_ACTIVE
+ tristate "Active Watermark"
+ help
+ Sets the frequency based on monitor watermark events.
+ This governor calculates relation between current load and
+ target load. The next frequency is calculated by multiplying
+ this relation with the current frequency.
+
+ The watermark values are updated so that the watermarks are
+ triggered when the above algorithm would change the frequency.
+
comment "DEVFREQ Drivers"
config ARM_EXYNOS4_BUS_DEVFREQ
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 92024eeb73b6..91e07aef3b29 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE) += governor_performance.o
obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE) += governor_powersave.o
obj-$(CONFIG_DEVFREQ_GOV_USERSPACE) += governor_userspace.o
obj-$(CONFIG_DEVFREQ_GOV_WMARK_SIMPLE) += governor_wmark_simple.o
+obj-$(CONFIG_DEVFREQ_GOV_WMARK_ACTIVE) += governor_wmark_active.o
# DEVFREQ Drivers
obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ) += exynos/
diff --git a/drivers/devfreq/governor_wmark_active.c b/drivers/devfreq/governor_wmark_active.c
new file mode 100644
index 000000000000..fe67d915d490
--- /dev/null
+++ b/drivers/devfreq/governor_wmark_active.c
@@ -0,0 +1,276 @@
+/*
+ * Copyright (c) 2014, NVIDIA CORPORATION. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/devfreq.h>
+#include <linux/debugfs.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+
+#include "governor.h"
+
+struct wmark_gov_info {
+ /* probed from the devfreq */
+ unsigned int *freqlist;
+ int freq_count;
+
+ /* algorithm parameters */
+ unsigned int p_load_target;
+ unsigned int p_load_max;
+
+ /* common data */
+ struct devfreq *df;
+ struct platform_device *pdev;
+ struct dentry *debugdir;
+};
+
+static unsigned int freqlist_up(struct wmark_gov_info *wmarkinfo,
+ unsigned int curr_freq)
+{
+ int i, pos;
+
+ for (i = 0; i < wmarkinfo->freq_count; i++)
+ if (wmarkinfo->freqlist[i] > curr_freq)
+ break;
+
+ pos = min(wmarkinfo->freq_count - 1, i);
+
+ return wmarkinfo->freqlist[pos];
+}
+
+static unsigned int freqlist_down(struct wmark_gov_info *wmarkinfo,
+ unsigned int curr_freq)
+{
+ int i, pos;
+
+ for (i = wmarkinfo->freq_count - 1; i >= 0; i--)
+ if (wmarkinfo->freqlist[i] < curr_freq)
+ break;
+
+ pos = max(0, i);
+ return wmarkinfo->freqlist[pos];
+}
+
+static unsigned int freqlist_round(struct wmark_gov_info *wmarkinfo,
+ unsigned int freq)
+{
+ int i, pos;
+
+ for (i = 0; i < wmarkinfo->freq_count; i++)
+ if (wmarkinfo->freqlist[i] >= freq)
+ break;
+
+ pos = min(wmarkinfo->freq_count - 1, i);
+ return wmarkinfo->freqlist[pos];
+}
+
+static void update_watermarks(struct devfreq *df,
+ unsigned int current_frequency)
+{
+ struct wmark_gov_info *wmarkinfo = df->data;
+ unsigned int relation = 0, next_freq = 0;
+ unsigned int current_frequency_khz = current_frequency / 1000;
+
+ if (current_frequency == wmarkinfo->freqlist[0]) {
+ /* disable the low watermark if we are at lowest clock */
+ df->profile->set_low_wmark(df->dev.parent, 0);
+ } else {
+ /* calculate the low threshold; what is the load value
+ * at which we would go into lower frequency given the
+ * that we are running at the new frequency? */
+ next_freq = freqlist_down(wmarkinfo, current_frequency);
+ relation = ((next_freq / current_frequency_khz) *
+ wmarkinfo->p_load_target) / 1000;
+ df->profile->set_low_wmark(df->dev.parent, relation);
+ }
+
+ if (current_frequency ==
+ wmarkinfo->freqlist[wmarkinfo->freq_count - 1]) {
+ /* disable the high watermark if we are at highest clock */
+ df->profile->set_high_wmark(df->dev.parent, 1000);
+ } else {
+ /* calculate the high threshold; what is the load value
+ * at which we would go into highest frequency given the
+ * that we are running at the new frequency? */
+ next_freq = freqlist_up(wmarkinfo, current_frequency);
+ relation = ((next_freq / current_frequency_khz) *
+ wmarkinfo->p_load_target) / 1000;
+ relation = min(wmarkinfo->p_load_max, relation);
+ df->profile->set_high_wmark(df->dev.parent, relation);
+ }
+
+}
+
+static int devfreq_watermark_target_freq(struct devfreq *df,
+ unsigned long *freq)
+{
+ struct wmark_gov_info *wmarkinfo = df->data;
+ struct devfreq_dev_status dev_stat;
+ unsigned int load, relation, next_freq;
+ int err;
+
+ err = df->profile->get_dev_status(df->dev.parent, &dev_stat);
+ if (err < 0)
+ return err;
+
+ /* keep current frequency if we do not have proper data available */
+ if (!dev_stat.total_time) {
+ *freq = dev_stat.current_frequency;
+ return 0;
+ }
+
+ /* calculate first load and relation load/p_load_target */
+ load = (dev_stat.busy_time * 1000) / dev_stat.total_time;
+
+ /* if we cross load max... */
+ if (load >= wmarkinfo->p_load_max) {
+ /* we go directly to the highest frequency. depending
+ * on frequency table we might never go higher than
+ * the current frequency (i.e. load should be over 100%
+ * to make relation push to the next frequency). */
+ *freq = wmarkinfo->freqlist[wmarkinfo->freq_count - 1];
+ } else {
+ /* otherwise, based on relation between current load and
+ * load target we calculate the "ideal" frequency
+ * where we would be just at the target */
+ relation = (load * 1000) / wmarkinfo->p_load_target;
+ next_freq = relation * (dev_stat.current_frequency / 1000);
+
+ /* round this frequency */
+ *freq = freqlist_round(wmarkinfo, next_freq);
+ }
+
+ /* update watermarks to match with the new frequency */
+ update_watermarks(df, *freq);
+
+ return 0;
+}
+
+static void devfreq_watermark_debug_start(struct devfreq *df)
+{
+ struct wmark_gov_info *wmarkinfo = df->data;
+ char dirname[128];
+
+ snprintf(dirname, sizeof(dirname), "%s_scaling",
+ to_platform_device(df->dev.parent)->name);
+
+ if (!wmarkinfo)
+ return;
+
+ wmarkinfo->debugdir = debugfs_create_dir(dirname, NULL);
+ if (!wmarkinfo->debugdir)
+ return;
+
+ debugfs_create_u32("load_target", S_IRUGO | S_IWUSR,
+ wmarkinfo->debugdir, &wmarkinfo->p_load_target);
+ debugfs_create_u32("load_max", S_IRUGO | S_IWUSR,
+ wmarkinfo->debugdir, &wmarkinfo->p_load_max);
+}
+
+static void devfreq_watermark_debug_stop(struct devfreq *df)
+{
+ struct wmark_gov_info *wmarkinfo = df->data;
+
+ debugfs_remove_recursive(wmarkinfo->debugdir);
+}
+
+static int devfreq_watermark_start(struct devfreq *df)
+{
+ struct wmark_gov_info *wmarkinfo;
+ struct platform_device *pdev = to_platform_device(df->dev.parent);
+
+ if (!df->profile->freq_table) {
+ dev_err(&pdev->dev, "Frequency table missing\n");
+ return -EINVAL;
+ }
+
+ wmarkinfo = kzalloc(sizeof(struct wmark_gov_info), GFP_KERNEL);
+ if (!wmarkinfo)
+ return -ENOMEM;
+
+ df->data = (void *)wmarkinfo;
+ wmarkinfo->freqlist = df->profile->freq_table;
+ wmarkinfo->freq_count = df->profile->max_state;
+ wmarkinfo->p_load_target = 700;
+ wmarkinfo->p_load_max = 900;
+ wmarkinfo->df = df;
+ wmarkinfo->pdev = pdev;
+
+ devfreq_watermark_debug_start(df);
+
+ return 0;
+}
+
+static int devfreq_watermark_event_handler(struct devfreq *df,
+ unsigned int event,
+ void *wmark_type)
+{
+ int ret = 0;
+ struct wmark_gov_info *wmarkinfo = df->data;
+
+ switch (event) {
+ case DEVFREQ_GOV_START:
+ devfreq_watermark_start(df);
+ wmarkinfo = df->data;
+ update_watermarks(df, wmarkinfo->freqlist[0]);
+ break;
+ case DEVFREQ_GOV_STOP:
+ devfreq_watermark_debug_stop(df);
+ break;
+ case DEVFREQ_GOV_SUSPEND:
+ devfreq_monitor_suspend(df);
+ break;
+
+ case DEVFREQ_GOV_RESUME:
+ wmarkinfo = df->data;
+ update_watermarks(df, wmarkinfo->freqlist[0]);
+ devfreq_monitor_resume(df);
+ break;
+
+ case DEVFREQ_GOV_WMARK:
+ mutex_lock(&df->lock);
+ update_devfreq(df);
+ mutex_unlock(&df->lock);
+ break;
+
+ default:
+ break;
+ }
+
+ return ret;
+}
+
+static struct devfreq_governor devfreq_watermark_active = {
+ .name = "wmark_active",
+ .get_target_freq = devfreq_watermark_target_freq,
+ .event_handler = devfreq_watermark_event_handler,
+};
+
+
+static int __init devfreq_watermark_init(void)
+{
+ return devfreq_add_governor(&devfreq_watermark_active);
+}
+
+static void __exit devfreq_watermark_exit(void)
+{
+ devfreq_remove_governor(&devfreq_watermark_active);
+}
+
+rootfs_initcall(devfreq_watermark_init);
+module_exit(devfreq_watermark_exit);
--
1.8.1.5
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [RFC RESEND 0/3] Add watermark support to devfreq
2014-12-05 13:41 [RFC RESEND 0/3] Add watermark support to devfreq Arto Merilainen
` (2 preceding siblings ...)
2014-12-05 13:41 ` [RFC RESEND 3/3] PM / devfreq: Add watermark active governor Arto Merilainen
@ 2014-12-09 13:25 ` Tomeu Vizoso
3 siblings, 0 replies; 7+ messages in thread
From: Tomeu Vizoso @ 2014-12-09 13:25 UTC (permalink / raw)
To: Arto Merilainen
Cc: MyungJoo Ham, Kyungmin Park, Alexandre Courbot,
Javier Martinez Canillas, linux-pm, linux-kernel, linux-tegra,
Stephen Warren, Thierry Reding, Grant Likely, srasal
On 5 December 2014 at 14:41, Arto Merilainen <amerilainen@nvidia.com> wrote:
> (Sorry for the spam. I am resending the series because I noted that
> some of the email addresses were mistyped)
>
> Currently main mechanism to implement scaling using devfreq is
> polling and the device profile is free to set polling interval.
> However, in many cases this approach is not optimal; We may
> unnecessarily use CPU time to determine load on engine that
> is idle most of time - or we may simply read load when we
> already know that the device is busy.
>
> In some cases a device itself has counters to track its activity
> and possibility to raise interrupts when load goes above or below
> certain threshold.
Hi Arto,
this is very interesting stuff, thanks for sending.
Regarding the question of whether the ACTMON driver should use this
generic governor, I think it comes down to whether we are able to
reach the best compromise between performance and power usage with it.
I see that the logic of the downstream ACTMON driver is much more
complex, as it takes into account the activity caused by the CPU
complex and gives it more weight than the total. It also sets
watermarks for the running average over the last 128 samples. The
frequency of the CPU is also taken into account.
Besides that, there's several factors and adjustments that I can only
think that have been determined through experimentation and
measurement and that in that case are very likely to be specific to a
given board and/or SoC.
It also takes into account consecutive watermark breaches and boosts
the frequency accordingly.
It would be great if you could ask within NVIDIA for the rationale
behind the way of calculating the target frequency downstream, as it
would allow us to better discern what can be made generic and what
belongs to the ACTMON driver itself.
It would be also good if we can find other SoCs that have similar
functionality, so we can make sure that what we end up adding to the
generic framework is of use to others.
Besides the above general points, two more specific comments:
* why not use the opp freq table from the DT (operating-points)
instead of freq_table?
* why having wmark_simple at all? And if we don't actually want it,
guess we can drop the event type arg?
Thanks,
Tomeu
> This series adds support for watermark events to devfreq and
> introduces two example governors. The first patch adds two
> callbacks to the device profile (for setting watermark) and
> adds a new function call to devfreq that informs of crossed
> watermark.
>
> The added governors demonstrate usage of the new API. The first
> governor (watermark simple) sets device to trigger low watermark
> event when load goes below 10% and high watermark interrupt when
> the load goes above 60%. Watermark active tries to keep load at
> certain level and it actively sets thresholds based on the
> frequency table in order get interrupts only when the load value
> would affect to the current frequency in re-estimation.
>
> Arto Merilainen (1):
> PM / devfreq: Add watermark active governor
>
> Shridhar Rasal (2):
> PM / devfreq: Add watermark events
> PM / devfreq: Add watermark simple governor
>
> drivers/devfreq/Kconfig | 18 +++
> drivers/devfreq/Makefile | 2 +
> drivers/devfreq/devfreq.c | 19 +++
> drivers/devfreq/governor.h | 1 +
> drivers/devfreq/governor_wmark_active.c | 276 ++++++++++++++++++++++++++++++++
> drivers/devfreq/governor_wmark_simple.c | 245 ++++++++++++++++++++++++++++
> include/linux/devfreq.h | 26 +++
> 7 files changed, 587 insertions(+)
> create mode 100644 drivers/devfreq/governor_wmark_active.c
> create mode 100644 drivers/devfreq/governor_wmark_simple.c
>
> --
> 1.8.1.5
>
> --
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^ permalink raw reply [flat|nested] 7+ messages in thread