Re: [Xen-devel] [RFC PATCH v3 01/24] NUMA: Make number of NUMA nodes configurable

[Vijay Kilari <vijay.kilari@xxxxxxxxx>]

On Tue, Jul 18, 2017 at 11:25 PM, Julien Grall <julien.grall@xxxxxxx> wrote:
> Hi,
>
>
> On 18/07/17 12:41, vijay.kilari@xxxxxxxxx wrote:
>>
>> From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
>>
>> Introduce NR_NODES config option to specify number
>> of NUMA nodes supported. By default value is set at
>> 64 for x86 and 8 for arm. Dropped NODES_SHIFT macro.
>>
>> Also move NR_NODE_MEMBLKS from asm-x86/acpi.h to xen/numa.h
>>
>> Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
>> ---
>>  xen/arch/Kconfig           | 7 +++++++
>>  xen/include/asm-x86/acpi.h | 1 -
>>  xen/include/asm-x86/numa.h | 2 --
>>  xen/include/xen/config.h   | 1 +
>>  xen/include/xen/numa.h     | 7 ++-----
>>  5 files changed, 10 insertions(+), 8 deletions(-)
>>
>> diff --git a/xen/arch/Kconfig b/xen/arch/Kconfig
>> index cf0acb7..9c2a4e2 100644
>> --- a/xen/arch/Kconfig
>> +++ b/xen/arch/Kconfig
>> @@ -6,3 +6,10 @@ config NR_CPUS
>>         default "128" if ARM
>>         ---help---
>>           Specifies the maximum number of physical CPUs which Xen will
>> support.
>> +
>> +config NR_NODES
>> +       int "Maximum number of NUMA nodes"
>> +       default "64" if X86
>> +       default "8" if ARM
>
>
> 3rd time I am asking it... Why the difference between x86 and ARM?

AFAIK, there is no arm platform for now with numa more than 8 nodes.
Thunderx is only 2 nodes.
So kept it low value for ARM to avoid unnecessary memory allocation.

Do you want me to keep same as x86?.

>
> Also, you likely want to set to 1 if NUMA is not enabled.

I don't see any dependency of NR_NODES with NUMA config.
So it is always set to default value. Isn't?

>
>
>> +       ---help---
>> +         Specifies the maximum number of NUMA nodes which Xen will
>> support.
>> diff --git a/xen/include/asm-x86/acpi.h b/xen/include/asm-x86/acpi.h
>> index 27ecc65..15be784 100644
>> --- a/xen/include/asm-x86/acpi.h
>> +++ b/xen/include/asm-x86/acpi.h
>> @@ -105,7 +105,6 @@ extern void acpi_reserve_bootmem(void);
>>
>>  extern s8 acpi_numa;
>>  extern int acpi_scan_nodes(u64 start, u64 end);
>> -#define NR_NODE_MEMBLKS (MAX_NUMNODES*2)
>>
>>  #ifdef CONFIG_ACPI_SLEEP
>>
>> diff --git a/xen/include/asm-x86/numa.h b/xen/include/asm-x86/numa.h
>> index bada2c0..3cf26c2 100644
>> --- a/xen/include/asm-x86/numa.h
>> +++ b/xen/include/asm-x86/numa.h
>> @@ -3,8 +3,6 @@
>>
>>  #include <xen/cpumask.h>
>>
>> -#define NODES_SHIFT 6
>> -
>>  typedef u8 nodeid_t;
>>
>>  extern int srat_rev;
>> diff --git a/xen/include/xen/config.h b/xen/include/xen/config.h
>> index a1d0f97..0f1a029 100644
>> --- a/xen/include/xen/config.h
>> +++ b/xen/include/xen/config.h
>> @@ -81,6 +81,7 @@
>>
>>  /* allow existing code to work with Kconfig variable */
>>  #define NR_CPUS CONFIG_NR_CPUS
>> +#define NR_NODES CONFIG_NR_NODES
>>
>>  #ifndef CONFIG_DEBUG
>>  #define NDEBUG
>> diff --git a/xen/include/xen/numa.h b/xen/include/xen/numa.h
>> index 7aef1a8..6bba29e 100644
>> --- a/xen/include/xen/numa.h
>> +++ b/xen/include/xen/numa.h
>> @@ -3,14 +3,11 @@
>>
>>  #include <asm/numa.h>
>>
>> -#ifndef NODES_SHIFT
>> -#define NODES_SHIFT     0
>> -#endif
>> -
>>  #define NUMA_NO_NODE     0xFF
>>  #define NUMA_NO_DISTANCE 0xFF
>>
>> -#define MAX_NUMNODES    (1 << NODES_SHIFT)
>> +#define MAX_NUMNODES    NR_NODES
>> +#define NR_NODE_MEMBLKS (MAX_NUMNODES * 2)
>>
>>  #define vcpu_to_node(v) (cpu_to_node((v)->processor))
>>
>>
>
> Cheers,
>
> --
> Julien Grall

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