Re: [Xen-devel] [RFC PATCH v1 18/21] ARM: NUMA: update node_distance with ACPI support

[Vijay Kilari <vijay.kilari@xxxxxxxxx>]

On Thu, Mar 2, 2017 at 10:54 PM, Julien Grall <julien.grall@xxxxxxx> wrote:
> Hello Vijay,
>
>
> On 09/02/17 15:57, vijay.kilari@xxxxxxxxx wrote:
>>
>> From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
>>
>> Update node_distance() function to handle
>> ACPI SLIT table information.
>>
>> Signed-off-by: Vijaya Kumar <Vijaya.Kumar@xxxxxxxxxx>
>> ---
>>  xen/arch/arm/numa.c | 20 +++++++++++++++++++-
>>  1 file changed, 19 insertions(+), 1 deletion(-)
>>
>> diff --git a/xen/arch/arm/numa.c b/xen/arch/arm/numa.c
>> index 5c49347..50c3dea 100644
>> --- a/xen/arch/arm/numa.c
>> +++ b/xen/arch/arm/numa.c
>> @@ -23,6 +23,7 @@
>>  #include <xen/acpi.h>
>>  #include <asm/mm.h>
>>  #include <xen/numa.h>
>> +#include <xen/srat.h>
>>  #include <asm/acpi.h>
>>  #include <xen/errno.h>
>>  #include <xen/cpumask.h>
>> @@ -35,6 +36,7 @@ extern struct node nodes[MAX_NUMNODES] __initdata;
>>  extern int num_node_memblks;
>>  extern struct node node_memblk_range[NR_NODE_MEMBLKS];
>>  extern nodeid_t memblk_nodeid[NR_NODE_MEMBLKS];
>> +extern struct acpi_table_slit *__read_mostly acpi_slit;
>>
>>  void __init numa_set_cpu_node(int cpu, unsigned long hwid)
>>  {
>> @@ -50,9 +52,24 @@ void __init numa_set_cpu_node(int cpu, unsigned long
>> hwid)
>>
>>  u8 __node_distance(nodeid_t a, nodeid_t b)
>>  {
>> -    if ( !node_distance )
>> +    unsigned index;
>> +    u8 slit_val;
>> +
>> +    if ( !node_distance && !acpi_slit )
>>          return a == b ? 10 : 20;
>>
>> +    if ( acpi_slit )
>> +    {
>> +        index = acpi_slit->locality_count * node_to_pxm(a);
>> +        slit_val = acpi_slit->entry[index + node_to_pxm(b)];
>> +
>> +        /* ACPI defines 0xff as an unreachable node and 0-9 are undefined
>> */
>> +        if ( (slit_val == 0xff) || (slit_val <= 9) )
>> +            return NUMA_NO_DISTANCE;
>> +        else
>> +            return slit_val;
>> +    }
>> +
>
>
> arm/numa.c is the generic code and should not contain any ACPI specific
> code.
Agreed.
>
> But as I said, the way to get the distance on ACPI is the same on x86 and
> ARM.
>
> So I would introduce __node_distance callback that will be setup at
> boot-time to either point to the ACPI version or DT version.

Instead of callback, Just call acpi's node_distance function if acpi is enabled
or else dt based.

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