[PATCH] ACPI: kernel-parameters.txt : Add intel_idle.max_cstate

[PATCH] ACPI: kernel-parameters.txt : Add intel_idle.max_cstate

[Masanari Iida]

Add missing intel_idle.max_cstate in kernel-parameters.txt

Signed-off-by Masanari Iida <standby24x7@gmail.com>
cc:Len Brown <lenb@kernel.org>
cc:Randy Dunlap <rdunlap@xenotime.net>
---
 Documentation/kernel-parameters.txt |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 81c287f..c6a56d8 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1035,6 +1035,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			By default, super page will be supported if Intel IOMMU
 			has the capability. With this option, super page will
 			not be supported.
+
+	intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
+			0	disables intel_idle and fall back on acpi_idle.
+			1 to 6	specify maximum depth of C-state.
+
 	intremap=	[X86-64, Intel-IOMMU]
 			on	enable Interrupt Remapping (default)
 			off	disable Interrupt Remapping
-- 
1.7.6.4

Re: [PATCH] ACPI: kernel-parameters.txt : Add intel_idle.max_cstate

[Thomas Renninger]

On Wednesday, December 14, 2011 05:18:52 PM Masanari Iida wrote:
> Add missing intel_idle.max_cstate in kernel-parameters.txt
I wonder whether this one should get documented at all.

Better would be to work towards a general cpuidle.max_state=
param which deprecates processor.max_cstate= (acpi_idle driver) and
intel_idle.max_cstate= and enables this functionality for all
other cpuidle drivers out there as well.

Something to turn off intel_idle driver and favor the acpi_idle
driver for debugging would still be needed then.

   Thomas

> 
> Signed-off-by Masanari Iida <standby24x7@gmail.com>
> cc:Len Brown <lenb@kernel.org>
> cc:Randy Dunlap <rdunlap@xenotime.net>
> ---
>  Documentation/kernel-parameters.txt |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-
parameters.txt
> index 81c287f..c6a56d8 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1035,6 +1035,11 @@ bytes respectively. Such letter suffixes can also 
be entirely omitted.
>  			By default, super page will be supported if Intel IOMMU
>  			has the capability. With this option, super page will
>  			not be supported.
> +
> +	intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
> +			0	disables intel_idle and fall back on acpi_idle.
> +			1 to 6	specify maximum depth of C-state.
> +
>  	intremap=	[X86-64, Intel-IOMMU]
>  			on	enable Interrupt Remapping (default)
>  			off	disable Interrupt Remapping
> -- 
> 1.7.6.4
> 
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Re: [PATCH] ACPI: kernel-parameters.txt : Add intel_idle.max_cstate

[Masanari Iida]

2011/12/16 Thomas Renninger <trenn@suse.de>:
> On Wednesday, December 14, 2011 05:18:52 PM Masanari Iida wrote:
>> Add missing intel_idle.max_cstate in kernel-parameters.txt
> I wonder whether this one should get documented at all.
>
My opinion is, as long as the kernel parameter is available,
we should document it.  And if developer want to guide the user to use
cpuidle.max_cstate, we should document so.

> Better would be to work towards a general cpuidle.max_state=
> param which deprecates processor.max_cstate= (acpi_idle driver) and
> intel_idle.max_cstate= and enables this functionality for all
> other cpuidle drivers out there as well.
>
cpuidle.max_state is also not in the kernel-parameters.txt,
Separate patch need to be created.

> Something to turn off intel_idle driver and favor the acpi_idle
> driver for debugging would still be needed then.
>
This patch explains how to disable intel_idle.
Although processor.max_cstate=0 sets cstate to 0,
but similar option intel_idle.max_cstate=0 didn't set cstate to 0.
This is confusing for the users.
This is the reason why I wanted to document it.

Masanari Iida

Re: [PATCH] ACPI: kernel-parameters.txt : Add intel_idle.max_cstate

[Len Brown]

you're both right.
document reality now,
make reality better later.

applied.

thanks,
-Len