Re: [RFC PATCH V1 1/7] cpuidle: create bootparam "cpuidle.off=1"

[Trinabh Gupta]

On 06/17/2011 09:59 AM, Benjamin Herrenschmidt wrote:
> On Tue, 2011-06-07 at 21:59 +0530, Trinabh Gupta wrote:
> > From: Len Brown<len.brown@xxxxxxxxx>
> >
> > useful for disabling cpuidle to fall back
> > to architecture-default idle loop
> >
> > cpuidle drivers and governors will fail to register.
> > on x86 they'll say so:
> >
> > intel_idle: intel_idle yielding to (null)
> > ACPI: acpi_idle yielding to (null)
> >
> > Signed-off-by: Len Brown<len.brown@xxxxxxxxx>
> > ---

Hi Ben,

Thanks for the review.
> When you carry over somebody's patch like this you need to also add your
> own signed-off-by.

Ok, thanks
> Have those generic changes been reviewed by whoever is in charge of that
> cpuidle framework ?

These patches were posted by Len Brown himself who is ACPI, Intel Idle
cpuidle driver maintainer. He pulled in most of the patches that were
part of that series (https://lkml.org/lkml/2011/4/2/8)
in 3.0-rc1, but these few patches are still out there. These changes
(removal of pm_idle) have already been agreed upon as they were
initially reported by Peter Zijlstra himself
(http://lkml.org/lkml/2009/8/28/43).

Thanks
-Trinabh
> Cheers,
> Ben.
>
> >   Documentation/kernel-parameters.txt |    3 +++
> >   drivers/cpuidle/cpuidle.c           |   10 ++++++++++
> >   drivers/cpuidle/cpuidle.h           |    1 +
> >   drivers/cpuidle/driver.c            |    3 +++
> >   drivers/cpuidle/governor.c          |    3 +++
> >   5 files changed, 20 insertions(+), 0 deletions(-)
> >
> > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> > index d9a203b..5697faf 100644
> > --- a/Documentation/kernel-parameters.txt
> > +++ b/Documentation/kernel-parameters.txt
> > @@ -546,6 +546,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> >   			/proc/<pid>/coredump_filter.
> >   			See also Documentation/filesystems/proc.txt.
> >
> > +	cpuidle.off=1	[CPU_IDLE]
> > +			disable the cpuidle sub-system
> > +
> >   	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
> >   			Format:
> >   			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
> > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> > index 406be83..a171b9e 100644
> > --- a/drivers/cpuidle/cpuidle.c
> > +++ b/drivers/cpuidle/cpuidle.c
> > @@ -28,6 +28,12 @@ LIST_HEAD(cpuidle_detected_devices);
> >   static void (*pm_idle_old)(void);
> >
> >   static int enabled_devices;
> > +static int off __read_mostly;
> > +
> > +int cpuidle_disabled(void)
> > +{
> > +	return off;
> > +}
> >
> >   #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
> >   static void cpuidle_kick_cpus(void)
> > @@ -397,6 +403,9 @@ static int __init cpuidle_init(void)
> >   {
> >   	int ret;
> >
> > +	if (cpuidle_disabled())
> > +		return -ENODEV;
> > +
> >   	pm_idle_old = pm_idle;
> >
> >   	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
> > @@ -408,4 +417,5 @@ static int __init cpuidle_init(void)
> >   	return 0;
> >   }
> >
> > +module_param(off, int, 0444);
> >   core_initcall(cpuidle_init);
> > diff --git a/drivers/cpuidle/cpuidle.h b/drivers/cpuidle/cpuidle.h
> > index 33e50d5..38c3fd8 100644
> > --- a/drivers/cpuidle/cpuidle.h
> > +++ b/drivers/cpuidle/cpuidle.h
> > @@ -13,6 +13,7 @@ extern struct list_head cpuidle_governors;
> >   extern struct list_head cpuidle_detected_devices;
> >   extern struct mutex cpuidle_lock;
> >   extern spinlock_t cpuidle_driver_lock;
> > +extern int cpuidle_disabled(void);
> >
> >   /* idle loop */
> >   extern void cpuidle_install_idle_handler(void);
> > diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
> > index 33e3189..284d7af 100644
> > --- a/drivers/cpuidle/driver.c
> > +++ b/drivers/cpuidle/driver.c
> > @@ -50,6 +50,9 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
> >   	if (!drv)
> >   		return -EINVAL;
> >
> > +	if (cpuidle_disabled())
> > +		return -ENODEV;
> > +
> >   	spin_lock(&cpuidle_driver_lock);
> >   	if (cpuidle_curr_driver) {
> >   		spin_unlock(&cpuidle_driver_lock);
> > diff --git a/drivers/cpuidle/governor.c b/drivers/cpuidle/governor.c
> > index 724c164..ea2f8e7 100644
> > --- a/drivers/cpuidle/governor.c
> > +++ b/drivers/cpuidle/governor.c
> > @@ -81,6 +81,9 @@ int cpuidle_register_governor(struct cpuidle_governor *gov)
> >   	if (!gov || !gov->select)
> >   		return -EINVAL;
> >
> > +	if (cpuidle_disabled())
> > +		return -ENODEV;
> > +
> >   	mutex_lock(&cpuidle_lock);
> >   	if (__cpuidle_find_governor(gov->name) == NULL) {
> >   		ret = 0;
> >
> > _______________________________________________
> > Linuxppc-dev mailing list
> > Linuxppc-dev@xxxxxxxxxxxxxxxx
> > https://lists.ozlabs.org/listinfo/linuxppc-dev
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