[PATCH 1/3] powerpc: Make NUMA depend on SMP

[PATCH 1/3] powerpc: Make NUMA depend on SMP

[Michael Ellerman]

Our Kconfig allows NUMA to be enabled without SMP, but none of
our defconfigs use that combination. This means it can easily be
broken inadvertently by code changes, which has happened recently.

Although it's theoretically possible to have a machine with a single
CPU and multiple memory nodes, I can't think of any real systems where
that's the case. Even so if such a system exists, it can just run an
SMP kernel anyway.

So to avoid the need to add extra #ifdefs and/or build breaks, make
NUMA depend on SMP.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e9f13fe08492..a22db3db6b96 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -660,7 +660,7 @@ config IRQ_ALL_CPUS
 
 config NUMA
 	bool "NUMA support"
-	depends on PPC64
+	depends on PPC64 && SMP
 	default y if SMP && PPC_PSERIES
 
 config NODES_SHIFT
-- 
2.25.1

[PATCH 2/3] powerpc: Make NUMA default y for powernv

[Michael Ellerman]

Our NUMA option is default y for pseries, but not powernv. The bulk of
powernv systems are NUMA, so make NUMA default y for powernv also.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a22db3db6b96..4d688b426353 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -661,7 +661,7 @@ config IRQ_ALL_CPUS
 config NUMA
 	bool "NUMA support"
 	depends on PPC64 && SMP
-	default y if SMP && PPC_PSERIES
+	default y if PPC_PSERIES || PPC_POWERNV
 
 config NODES_SHIFT
 	int
-- 
2.25.1

[PATCH 3/3] powerpc: Update NUMA Kconfig description & help text

[Michael Ellerman]

Update the NUMA Kconfig description to match other architectures, and
add some help text. Shamelessly borrowed from x86/arm64.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/Kconfig | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 4d688b426353..7f4995b245a3 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -659,9 +659,15 @@ config IRQ_ALL_CPUS
 	  reported with SMP Power Macintoshes with this option enabled.
 
 config NUMA
-	bool "NUMA support"
+	bool "NUMA Memory Allocation and Scheduler Support"
 	depends on PPC64 && SMP
 	default y if PPC_PSERIES || PPC_POWERNV
+	help
+	  Enable NUMA (Non-Uniform Memory Access) support.
+
+	  The kernel will try to allocate memory used by a CPU on the
+	  local memory controller of the CPU and add some more
+	  NUMA awareness to the kernel.
 
 config NODES_SHIFT
 	int
-- 
2.25.1

Re: [PATCH 1/3] powerpc: Make NUMA depend on SMP

[Randy Dunlap]

On 11/24/20 4:05 AM, Michael Ellerman wrote:
> Our Kconfig allows NUMA to be enabled without SMP, but none of
> our defconfigs use that combination. This means it can easily be
> broken inadvertently by code changes, which has happened recently.
> 
> Although it's theoretically possible to have a machine with a single
> CPU and multiple memory nodes, I can't think of any real systems where
> that's the case. Even so if such a system exists, it can just run an
> SMP kernel anyway.
> 
> So to avoid the need to add extra #ifdefs and/or build breaks, make
> NUMA depend on SMP.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>

Thanks.

> ---
>  arch/powerpc/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index e9f13fe08492..a22db3db6b96 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -660,7 +660,7 @@ config IRQ_ALL_CPUS
>  
>  config NUMA
>  	bool "NUMA support"
> -	depends on PPC64
> +	depends on PPC64 && SMP
>  	default y if SMP && PPC_PSERIES
>  
>  config NODES_SHIFT
> 


-- 
~Randy

Re: [PATCH 3/3] powerpc: Update NUMA Kconfig description & help text

[Randy Dunlap]

On 11/24/20 4:05 AM, Michael Ellerman wrote:
> Update the NUMA Kconfig description to match other architectures, and
> add some help text. Shamelessly borrowed from x86/arm64.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>

Thanks.

> ---
>  arch/powerpc/Kconfig | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 4d688b426353..7f4995b245a3 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -659,9 +659,15 @@ config IRQ_ALL_CPUS
>  	  reported with SMP Power Macintoshes with this option enabled.
>  
>  config NUMA
> -	bool "NUMA support"
> +	bool "NUMA Memory Allocation and Scheduler Support"
>  	depends on PPC64 && SMP
>  	default y if PPC_PSERIES || PPC_POWERNV
> +	help
> +	  Enable NUMA (Non-Uniform Memory Access) support.
> +
> +	  The kernel will try to allocate memory used by a CPU on the
> +	  local memory controller of the CPU and add some more
> +	  NUMA awareness to the kernel.
>  
>  config NODES_SHIFT
>  	int
> 


-- 
~Randy

Re: [PATCH 1/3] powerpc: Make NUMA depend on SMP

[Srikar Dronamraju]

* Michael Ellerman <mpe@ellerman.id.au> [2020-11-24 23:05:45]:

> Our Kconfig allows NUMA to be enabled without SMP, but none of
> our defconfigs use that combination. This means it can easily be
> broken inadvertently by code changes, which has happened recently.
> 
> Although it's theoretically possible to have a machine with a single
> CPU and multiple memory nodes, I can't think of any real systems where
> that's the case. Even so if such a system exists, it can just run an
> SMP kernel anyway.
> 
> So to avoid the need to add extra #ifdefs and/or build breaks, make
> NUMA depend on SMP.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Looks good to me.

Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> ---
>  arch/powerpc/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index e9f13fe08492..a22db3db6b96 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -660,7 +660,7 @@ config IRQ_ALL_CPUS
> 
>  config NUMA
>  	bool "NUMA support"
> -	depends on PPC64
> +	depends on PPC64 && SMP
>  	default y if SMP && PPC_PSERIES
> 
>  config NODES_SHIFT
> -- 
> 2.25.1
> 

-- 
Thanks and Regards
Srikar Dronamraju

Re: [PATCH 2/3] powerpc: Make NUMA default y for powernv

[Srikar Dronamraju]

* Michael Ellerman <mpe@ellerman.id.au> [2020-11-24 23:05:46]:

> Our NUMA option is default y for pseries, but not powernv. The bulk of
> powernv systems are NUMA, so make NUMA default y for powernv also.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Looks good to me.

Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> ---
>  arch/powerpc/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index a22db3db6b96..4d688b426353 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -661,7 +661,7 @@ config IRQ_ALL_CPUS
>  config NUMA
>  	bool "NUMA support"
>  	depends on PPC64 && SMP
> -	default y if SMP && PPC_PSERIES
> +	default y if PPC_PSERIES || PPC_POWERNV
> 
>  config NODES_SHIFT
>  	int
> -- 
> 2.25.1
> 

-- 
Thanks and Regards
Srikar Dronamraju

Re: [PATCH 1/3] powerpc: Make NUMA depend on SMP

[Michael Ellerman]

On Tue, 24 Nov 2020 23:05:45 +1100, Michael Ellerman wrote:
> Our Kconfig allows NUMA to be enabled without SMP, but none of
> our defconfigs use that combination. This means it can easily be
> broken inadvertently by code changes, which has happened recently.
> 
> Although it's theoretically possible to have a machine with a single
> CPU and multiple memory nodes, I can't think of any real systems where
> that's the case. Even so if such a system exists, it can just run an
> SMP kernel anyway.
> 
> [...]

Applied to powerpc/next.

[1/3] powerpc: Make NUMA depend on SMP
      https://git.kernel.org/powerpc/c/25395cd2f8cb24ce6a5ce073c898acfb091e06cf
[2/3] powerpc: Make NUMA default y for powernv
      https://git.kernel.org/powerpc/c/4c28b32b886f1489c5f510ed8e3f0c4e3dcb59f5
[3/3] powerpc: Update NUMA Kconfig description & help text
      https://git.kernel.org/powerpc/c/bae80c27fc2195b9e5723d7b05c592e0874f4ba9

cheers