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[PATCH v1 2/2] PM: Add config flag to gate sysfs wakeup_sources

Samuel Wu posted 2 patches 2 weeks, 2 days ago
[PATCH v1 2/2] PM: Add config flag to gate sysfs wakeup_sources
Posted by Samuel Wu 2 weeks, 2 days ago 
Add a config flag that gates the creation of
/sys/class/wakeup_sources/*. This has the benefit of eliminating the
work needed to create the nodes and corresponding attributes; and
between kernfs, dentry, and malloc, there are some memory savings
depending on the number of wakeup sources.

Signed-off-by: Samuel Wu <wusamuel@google.com>
---
 drivers/base/power/Makefile |  3 ++-
 drivers/base/power/power.h  | 14 ++++++++++++++
 kernel/power/Kconfig        | 13 +++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 2989e42d0161..5933dadc0dd9 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_PM)	+= sysfs.o generic_ops.o common.o qos.o runtime.o wakeirq.o
-obj-$(CONFIG_PM_SLEEP)	+= main.o wakeup.o wakeup_stats.o
+obj-$(CONFIG_PM_SLEEP)	+= main.o wakeup.o
+obj-$(CONFIG_PM_WAKEUP_STATS_SYSFS)	+= wakeup_stats.o
 obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o
 obj-$(CONFIG_HAVE_CLK)	+= clock_ops.o
 obj-$(CONFIG_PM_QOS_KUNIT_TEST) += qos-test.o
diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index 922ed457db19..364ca5512b4f 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -125,11 +125,25 @@ static inline bool device_pm_initialized(struct device *dev)
 }
 
 /* drivers/base/power/wakeup_stats.c */
+#ifdef CONFIG_PM_WAKEUP_STATS_SYSFS
 extern int wakeup_source_sysfs_add(struct device *parent,
 				   struct wakeup_source *ws);
 extern void wakeup_source_sysfs_remove(struct wakeup_source *ws);
 
 extern int pm_wakeup_source_sysfs_add(struct device *parent);
+#else /* !CONFIG_PM_WAKEUP_STATS_SYSFS */
+static inline int wakeup_source_sysfs_add(struct device *parent,
+					  struct wakeup_source *ws)
+{
+	return 0;
+}
+static inline void wakeup_source_sysfs_remove(struct wakeup_source *ws) {}
+
+static inline int pm_wakeup_source_sysfs_add(struct device *parent)
+{
+	return 0;
+}
+#endif /* !CONFIG_PM_WAKEUP_STATS_SYSFS */
 
 #else /* !CONFIG_PM_SLEEP */
 
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 05337f437cca..6945083ab053 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -202,6 +202,19 @@ config PM_WAKELOCKS_GC
 	depends on PM_WAKELOCKS
 	default y
 
+config PM_WAKEUP_STATS_SYSFS
+	bool "Sysfs wakeup statistics"
+	depends on PM_SLEEP
+	default y
+	help
+	  Enable this for wakeup statistics in sysfs under /sys/class/wakeup/
+
+	  Disabling this option eliminates the work of creating the wakeup
+	  sources and each of their attributes in sysfs. Depending on the
+	  number of wakeup sources, this can also have a non-negligible memory
+	  impact. Regardless of this config option's value, wakeup statistics
+	  are still available via debugfs and BPF.
+
 config PM_QOS_CPU_SYSTEM_WAKEUP
 	bool "User space interface for CPU system wakeup QoS"
 	depends on CPU_IDLE
-- 
2.53.0.959.g497ff81fa9-goog
Re: [PATCH v1 2/2] PM: Add config flag to gate sysfs wakeup_sources
Posted by Rafael J. Wysocki 2 weeks, 2 days ago 
On Fri, Mar 20, 2026 at 5:01 PM Samuel Wu <wusamuel@google.com> wrote:
>
> Add a config flag that gates the creation of
> /sys/class/wakeup_sources/*. This has the benefit of eliminating the
> work needed to create the nodes and corresponding attributes; and
> between kernfs, dentry, and malloc, there are some memory savings
> depending on the number of wakeup sources.
>
> Signed-off-by: Samuel Wu <wusamuel@google.com>
> ---
>  drivers/base/power/Makefile |  3 ++-
>  drivers/base/power/power.h  | 14 ++++++++++++++
>  kernel/power/Kconfig        | 13 +++++++++++++
>  3 files changed, 29 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
> index 2989e42d0161..5933dadc0dd9 100644
> --- a/drivers/base/power/Makefile
> +++ b/drivers/base/power/Makefile
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-$(CONFIG_PM)       += sysfs.o generic_ops.o common.o qos.o runtime.o wakeirq.o
> -obj-$(CONFIG_PM_SLEEP) += main.o wakeup.o wakeup_stats.o
> +obj-$(CONFIG_PM_SLEEP) += main.o wakeup.o
> +obj-$(CONFIG_PM_WAKEUP_STATS_SYSFS)    += wakeup_stats.o
>  obj-$(CONFIG_PM_TRACE_RTC)     += trace.o
>  obj-$(CONFIG_HAVE_CLK) += clock_ops.o
>  obj-$(CONFIG_PM_QOS_KUNIT_TEST) += qos-test.o
> diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
> index 922ed457db19..364ca5512b4f 100644
> --- a/drivers/base/power/power.h
> +++ b/drivers/base/power/power.h
> @@ -125,11 +125,25 @@ static inline bool device_pm_initialized(struct device *dev)
>  }
>
>  /* drivers/base/power/wakeup_stats.c */
> +#ifdef CONFIG_PM_WAKEUP_STATS_SYSFS
>  extern int wakeup_source_sysfs_add(struct device *parent,
>                                    struct wakeup_source *ws);
>  extern void wakeup_source_sysfs_remove(struct wakeup_source *ws);
>
>  extern int pm_wakeup_source_sysfs_add(struct device *parent);
> +#else /* !CONFIG_PM_WAKEUP_STATS_SYSFS */
> +static inline int wakeup_source_sysfs_add(struct device *parent,
> +                                         struct wakeup_source *ws)
> +{
> +       return 0;
> +}
> +static inline void wakeup_source_sysfs_remove(struct wakeup_source *ws) {}
> +
> +static inline int pm_wakeup_source_sysfs_add(struct device *parent)
> +{
> +       return 0;
> +}
> +#endif /* !CONFIG_PM_WAKEUP_STATS_SYSFS */
>
>  #else /* !CONFIG_PM_SLEEP */
>
> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> index 05337f437cca..6945083ab053 100644
> --- a/kernel/power/Kconfig
> +++ b/kernel/power/Kconfig
> @@ -202,6 +202,19 @@ config PM_WAKELOCKS_GC
>         depends on PM_WAKELOCKS
>         default y
>
> +config PM_WAKEUP_STATS_SYSFS
> +       bool "Sysfs wakeup statistics"
> +       depends on PM_SLEEP
> +       default y
> +       help
> +         Enable this for wakeup statistics in sysfs under /sys/class/wakeup/
> +
> +         Disabling this option eliminates the work of creating the wakeup
> +         sources and each of their attributes in sysfs. Depending on the
> +         number of wakeup sources, this can also have a non-negligible memory
> +         impact. Regardless of this config option's value, wakeup statistics
> +         are still available via debugfs and BPF.

Well, except that otherwise it may be hard to figure out which device
the given wakeup source belongs to, so I'd rather not do that.

> +
>  config PM_QOS_CPU_SYSTEM_WAKEUP
>         bool "User space interface for CPU system wakeup QoS"
>         depends on CPU_IDLE
> --
Re: [PATCH v1 2/2] PM: Add config flag to gate sysfs wakeup_sources
Posted by Samuel Wu 2 weeks, 2 days ago 
On Fri, Mar 20, 2026 at 9:09 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
>

[ ... ]

> >
> > +config PM_WAKEUP_STATS_SYSFS
> > +       bool "Sysfs wakeup statistics"
> > +       depends on PM_SLEEP
> > +       default y
> > +       help
> > +         Enable this for wakeup statistics in sysfs under /sys/class/wakeup/
> > +
> > +         Disabling this option eliminates the work of creating the wakeup
> > +         sources and each of their attributes in sysfs. Depending on the
> > +         number of wakeup sources, this can also have a non-negligible memory
> > +         impact. Regardless of this config option's value, wakeup statistics
> > +         are still available via debugfs and BPF.
>
> Well, except that otherwise it may be hard to figure out which device
> the given wakeup source belongs to, so I'd rather not do that.
>

Since the config flag defaults to yes, this wouldn't affect current
users right? And then the idea is that other users who don't need this
sysfs node can turn the flag off to save some cycles and memory.

[ ... ]

Patchew 2.1-devel-ea86937

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