docs: Update nosmt support for arm64

[PATCH] docs: Update nosmt support for arm64

Posted by Jinjie Ruan 2 months ago

commit eed4583bcf9a6 ("arm64: Kconfig: Enable HOTPLUG_SMT") enable
HOTPLUG_SMT for SMT control for arm64, but the documentation was
not updated accordingly to reflect that ARM64 now supports control SMT
via boot parameter and sysfs knobs:

1. Boot parameters:

nosmt:          Disable SMT, can be enabled via sysfs knobs.
nosmt=force:    Disable SMT, cannot be enabled via sysfs knobs.

2. Runtime sysfs controls:

Write "on", "off", "forceoff" or the number of SMT threads (1, 2, ...)
to /sys/devices/system/cpu/smt/control.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index cb850e5290c2..6a73eb5abae9 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4661,7 +4661,7 @@ Kernel parameters
 	nosmt		[KNL,MIPS,PPC,EARLY] Disable symmetric multithreading (SMT).
 			Equivalent to smt=1.
 
-			[KNL,LOONGARCH,X86,PPC,S390] Disable symmetric multithreading (SMT).
+			[KNL,LOONGARCH,X86,ARM64,PPC,S390] Disable symmetric multithreading (SMT).
 			nosmt=force: Force disable SMT, cannot be undone
 				     via the sysfs control file.
 
-- 
2.34.1

Re: [PATCH] docs: Update nosmt support for arm64

Posted by Jonathan Corbet 1 month ago

Jinjie Ruan <ruanjinjie@huawei.com> writes:

> commit eed4583bcf9a6 ("arm64: Kconfig: Enable HOTPLUG_SMT") enable
> HOTPLUG_SMT for SMT control for arm64, but the documentation was
> not updated accordingly to reflect that ARM64 now supports control SMT
> via boot parameter and sysfs knobs:
>
> 1. Boot parameters:
>
> nosmt:          Disable SMT, can be enabled via sysfs knobs.
> nosmt=force:    Disable SMT, cannot be enabled via sysfs knobs.
>
> 2. Runtime sysfs controls:
>
> Write "on", "off", "forceoff" or the number of SMT threads (1, 2, ...)
> to /sys/devices/system/cpu/smt/control.
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index cb850e5290c2..6a73eb5abae9 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4661,7 +4661,7 @@ Kernel parameters
>  	nosmt		[KNL,MIPS,PPC,EARLY] Disable symmetric multithreading (SMT).
>  			Equivalent to smt=1.
>  
> -			[KNL,LOONGARCH,X86,PPC,S390] Disable symmetric multithreading (SMT).
> +			[KNL,LOONGARCH,X86,ARM64,PPC,S390] Disable symmetric multithreading (SMT).

Applied, thanks.

jon

Re: [PATCH] docs: Update nosmt support for arm64

Posted by Jinjie Ruan 1 month ago

Gentle ping.

On 4/17/2026 11:25 AM, Jinjie Ruan wrote:
> commit eed4583bcf9a6 ("arm64: Kconfig: Enable HOTPLUG_SMT") enable
> HOTPLUG_SMT for SMT control for arm64, but the documentation was
> not updated accordingly to reflect that ARM64 now supports control SMT
> via boot parameter and sysfs knobs:
> 
> 1. Boot parameters:
> 
> nosmt:          Disable SMT, can be enabled via sysfs knobs.
> nosmt=force:    Disable SMT, cannot be enabled via sysfs knobs.
> 
> 2. Runtime sysfs controls:
> 
> Write "on", "off", "forceoff" or the number of SMT threads (1, 2, ...)
> to /sys/devices/system/cpu/smt/control.
> 
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index cb850e5290c2..6a73eb5abae9 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4661,7 +4661,7 @@ Kernel parameters
>  	nosmt		[KNL,MIPS,PPC,EARLY] Disable symmetric multithreading (SMT).
>  			Equivalent to smt=1.
>  
> -			[KNL,LOONGARCH,X86,PPC,S390] Disable symmetric multithreading (SMT).
> +			[KNL,LOONGARCH,X86,ARM64,PPC,S390] Disable symmetric multithreading (SMT).
>  			nosmt=force: Force disable SMT, cannot be undone
>  				     via the sysfs control file.
>