[PATCH] thp: 'transparent_hugepage=' can also be specified on cmdline

[PATCH] thp: 'transparent_hugepage=' can also be specified on cmdline

[Jiri Kosina]

Behavior of THP can either be toggled through sysfs in runtime or using a 
kernel cmdline parameter 'transparent_hugepage='. Document the latter.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---
 Documentation/kernel-parameters.txt |    7 +++++++
 Documentation/vm/transhuge.txt      |    3 +++
 2 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 033d4e6..a4de9b9 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2629,6 +2629,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			to facilitate early boot debugging.
 			See also Documentation/trace/events.txt
 
+	transparent_hugepage=
+			[KNL]
+			Format: [always|madvise|never]
+			Can be used to control the default behavior of the system
+			with respect to transparent hugepages.
+			See Documentation/vm/transhuge.txt for more details.
+
 	tsc=		Disable clocksource stability checks for TSC.
 			Format: <string>
 			[x86] reliable: mark tsc clocksource as reliable, this
diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt
index 29bdf62..4a3816d 100644
--- a/Documentation/vm/transhuge.txt
+++ b/Documentation/vm/transhuge.txt
@@ -103,6 +103,9 @@ echo always >/sys/kernel/mm/transparent_hugepage/enabled
 echo madvise >/sys/kernel/mm/transparent_hugepage/enabled
 echo never >/sys/kernel/mm/transparent_hugepage/enabled
 
+The always/madvise/never value can also be specified on the kernel boot
+commandline using 'transparent_hugepage=' parameter.
+
 It's also possible to limit defrag efforts in the VM to generate
 hugepages in case they're not immediately free to madvise regions or
 to never try to defrag memory and simply fallback to regular pages
-- 
1.7.3.1

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Re: [PATCH] thp: 'transparent_hugepage=' can also be specified on cmdline

[Andrea Arcangeli]

On Wed, Feb 22, 2012 at 05:13:04PM +0100, Jiri Kosina wrote:
> Behavior of THP can either be toggled through sysfs in runtime or using a 
> kernel cmdline parameter 'transparent_hugepage='. Document the latter.
> 
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
> ---
>  Documentation/kernel-parameters.txt |    7 +++++++
>  Documentation/vm/transhuge.txt      |    3 +++
>  2 files changed, 10 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 033d4e6..a4de9b9 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -2629,6 +2629,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  			to facilitate early boot debugging.
>  			See also Documentation/trace/events.txt
>  
> +	transparent_hugepage=
> +			[KNL]
> +			Format: [always|madvise|never]
> +			Can be used to control the default behavior of the system
> +			with respect to transparent hugepages.
> +			See Documentation/vm/transhuge.txt for more details.
> +
>  	tsc=		Disable clocksource stability checks for TSC.
>  			Format: <string>
>  			[x86] reliable: mark tsc clocksource as reliable, this

Ok.

> diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt
> index 29bdf62..4a3816d 100644
> --- a/Documentation/vm/transhuge.txt
> +++ b/Documentation/vm/transhuge.txt
> @@ -103,6 +103,9 @@ echo always >/sys/kernel/mm/transparent_hugepage/enabled
>  echo madvise >/sys/kernel/mm/transparent_hugepage/enabled
>  echo never >/sys/kernel/mm/transparent_hugepage/enabled
>  
> +The always/madvise/never value can also be specified on the kernel boot
> +commandline using 'transparent_hugepage=' parameter.
> +
>  It's also possible to limit defrag efforts in the VM to generate

This is a dup.

== Boot parameter ==

You can change the sysfs boot time defaults of Transparent Hugepage
Support by passing the parameter "transparent_hugepage=always" or
"transparent_hugepage=madvise" or "transparent_hugepage=never"
(without "") to the kernel command line.


>  hugepages in case they're not immediately free to madvise regions or
>  to never try to defrag memory and simply fallback to regular pages
> -- 
> 1.7.3.1
> 

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Re: [PATCH] thp: 'transparent_hugepage=' can also be specified on cmdline

[Jiri Kosina]

On Wed, 22 Feb 2012, Andrea Arcangeli wrote:

> > diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt
> > index 29bdf62..4a3816d 100644
> > --- a/Documentation/vm/transhuge.txt
> > +++ b/Documentation/vm/transhuge.txt
> > @@ -103,6 +103,9 @@ echo always >/sys/kernel/mm/transparent_hugepage/enabled
> >  echo madvise >/sys/kernel/mm/transparent_hugepage/enabled
> >  echo never >/sys/kernel/mm/transparent_hugepage/enabled
> >  
> > +The always/madvise/never value can also be specified on the kernel boot
> > +commandline using 'transparent_hugepage=' parameter.
> > +
> >  It's also possible to limit defrag efforts in the VM to generate
> 
> This is a dup.

I am blind and you are right.

v2 below. Thanks.



From: Jiri Kosina <jkosina@suse.cz>
Subject: [PATCH] thp: 'transparent_hugepage=' can also be specified on cmdline

Behavior of THP can either be toggled through sysfs in runtime or using a 
kernel cmdline parameter 'transparent_hugepage='. Document the latter in 
kernel-parameters.txt

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---
 Documentation/kernel-parameters.txt |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 033d4e6..a4de9b9 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2629,6 +2629,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			to facilitate early boot debugging.
 			See also Documentation/trace/events.txt
 
+	transparent_hugepage=
+			[KNL]
+			Format: [always|madvise|never]
+			Can be used to control the default behavior of the system
+			with respect to transparent hugepages.
+			See Documentation/vm/transhuge.txt for more details.
+
 	tsc=		Disable clocksource stability checks for TSC.
 			Format: <string>
 			[x86] reliable: mark tsc clocksource as reliable, this

-- 
Jiri Kosina
SUSE Labs

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