From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Len Brown <lenb@kernel.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Doug Smythies <dsmythies@telus.net>,
LKML <linux-kernel@vger.kernel.org>
Subject: [RFC][PATCH 2/2] cpuidle: Allow idle states to be disabled by default
Date: Tue, 19 Nov 2019 00:09:47 +0100 [thread overview]
Message-ID: <5713675.uzLynPL2dK@kreacher> (raw)
In-Reply-To: <1688511.GgkECGP1XA@kreacher>
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In certain situations it may be useful to prevent some idle states
from being used by default while allowing user space to enable them
later on.
For this purpose, introduce a new state flag, CPUIDLE_FLAG_UNCERTAIN,
to mark idle states that should be disabled by default, make the
core set CPUIDLE_STATE_DISABLED_BY_USER for those states at the
initialization time and add a new state attribute in sysfs,
"disable_default", to provide user space with the default value
of the "disable" attribute (1 if CPUIDLE_FLAG_UNCERTAIN is set for
the given state, 0 otherwise) to allow it to restore the initial
configuration of idle states easily if need be.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
Documentation/ABI/testing/sysfs-devices-system-cpu | 6 ++++++
Documentation/admin-guide/pm/cpuidle.rst | 3 +++
drivers/cpuidle/cpuidle.c | 3 +++
drivers/cpuidle/sysfs.c | 9 +++++++++
include/linux/cpuidle.h | 1 +
5 files changed, 22 insertions(+)
Index: linux-pm/drivers/cpuidle/sysfs.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/sysfs.c
+++ linux-pm/drivers/cpuidle/sysfs.c
@@ -327,6 +327,13 @@ static ssize_t store_state_disable(struc
return size;
}
+static ssize_t show_state_disable_default(struct cpuidle_state *state,
+ struct cpuidle_state_usage *state_usage,
+ char *buf)
+{
+ return sprintf(buf, "%u\n", !!(state->flags & CPUIDLE_FLAG_UNCERTAIN));
+}
+
define_one_state_ro(name, show_state_name);
define_one_state_ro(desc, show_state_desc);
define_one_state_ro(latency, show_state_exit_latency);
@@ -337,6 +344,7 @@ define_one_state_ro(time, show_state_tim
define_one_state_rw(disable, show_state_disable, store_state_disable);
define_one_state_ro(above, show_state_above);
define_one_state_ro(below, show_state_below);
+define_one_state_ro(disable_default, show_state_disable_default);
static struct attribute *cpuidle_state_default_attrs[] = {
&attr_name.attr,
@@ -347,6 +355,7 @@ static struct attribute *cpuidle_state_d
&attr_usage.attr,
&attr_time.attr,
&attr_disable.attr,
+ &attr_disable_default.attr,
&attr_above.attr,
&attr_below.attr,
NULL
Index: linux-pm/include/linux/cpuidle.h
===================================================================
--- linux-pm.orig/include/linux/cpuidle.h
+++ linux-pm/include/linux/cpuidle.h
@@ -77,6 +77,7 @@ struct cpuidle_state {
#define CPUIDLE_FLAG_COUPLED BIT(1) /* state applies to multiple cpus */
#define CPUIDLE_FLAG_TIMER_STOP BIT(2) /* timer is stopped on this state */
#define CPUIDLE_FLAG_UNUSABLE BIT(3) /* avoid using this state */
+#define CPUIDLE_FLAG_UNCERTAIN BIT(4) /* disable this state by default */
struct cpuidle_device_kobj;
struct cpuidle_state_kobj;
Index: linux-pm/drivers/cpuidle/cpuidle.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/cpuidle.c
+++ linux-pm/drivers/cpuidle/cpuidle.c
@@ -572,6 +572,9 @@ static int __cpuidle_register_device(str
for (i = 0; i < drv->state_count; i++) {
if (drv->states[i].flags & CPUIDLE_FLAG_UNUSABLE)
dev->states_usage[i].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;
+
+ if (drv->states[i].flags & CPUIDLE_FLAG_UNCERTAIN)
+ dev->states_usage[i].disable |= CPUIDLE_STATE_DISABLED_BY_USER;
}
per_cpu(cpuidle_devices, dev->cpu) = dev;
Index: linux-pm/Documentation/ABI/testing/sysfs-devices-system-cpu
===================================================================
--- linux-pm.orig/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ linux-pm/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -196,6 +196,12 @@ Description:
does not reflect it. Likewise, if one enables a deep state but a
lighter state still is disabled, then this has no effect.
+What: /sys/devices/system/cpu/cpuX/cpuidle/stateN/disable_dafault
+Date: November 2019
+KernelVersion: v5.4
+Contact: Linux power management list <linux-pm@vger.kernel.org>
+Description:
+ (RO) The default value of the disable state attribute (bool).
What: /sys/devices/system/cpu/cpuX/cpuidle/stateN/residency
Date: March 2014
Index: linux-pm/Documentation/admin-guide/pm/cpuidle.rst
===================================================================
--- linux-pm.orig/Documentation/admin-guide/pm/cpuidle.rst
+++ linux-pm/Documentation/admin-guide/pm/cpuidle.rst
@@ -506,6 +506,9 @@ object corresponding to it, as follows:
``disable``
Whether or not this idle state is disabled.
+``disable_default``
+ The default value of the ``disable`` attribute.
+
``latency``
Exit latency of the idle state in microseconds.
prev parent reply other threads:[~2019-11-18 23:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-04 11:16 [PATCH] cpuidle: Consolidate disabled state checks Rafael J. Wysocki
2019-11-04 11:52 ` Peter Zijlstra
2019-11-18 4:45 ` Len Brown
2019-11-18 9:22 ` Rafael J. Wysocki
2019-11-18 11:26 ` Rafael J. Wysocki
2019-11-18 23:04 ` [RFC][PATCH 0/2] cpuidle: Allow states to be disabled by default (was: Re: [PATCH] cpuidle: Consolidate disabled state checks) Rafael J. Wysocki
2019-11-18 23:07 ` [RFC][PATCH 1/2] cpuidle: Drop disabled field from struct cpuidle_state Rafael J. Wysocki
2019-11-18 23:09 ` Rafael J. Wysocki [this message]
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