Re: [PATCH v4 1/9] numa: __node_distance() should return u8

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 03/10/2015 07:53 AM, Andrew Cooper wrote:
> On 10/03/15 02:27, Boris Ostrovsky wrote:
>> SLIT values are byte-sized and some of them (0-9 and 255) have
>> special meaning. Adjust __node_distance() to reflect this and
>> modify scrub_heap_pages() to deal with __node_distance() returning
>> an invalid SLIT entry.
>>
>> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> You also need to teach XEN_SYSCTL_numainfo about the new NUMA_NO_DISTANCE.

The sysctl is updated later in the series but this may indeed break 
bisection.

>
>> ---
>>   xen/arch/x86/srat.c        |   15 +++++++++++----
>>   xen/common/page_alloc.c    |    4 ++--
>>   xen/include/asm-x86/numa.h |    2 +-
>>   xen/include/xen/numa.h     |    3 ++-
>>   4 files changed, 16 insertions(+), 8 deletions(-)
>>
>> diff --git a/xen/arch/x86/srat.c b/xen/arch/x86/srat.c
>> index dfabba3..aa2eda3 100644
>> --- a/xen/arch/x86/srat.c
>> +++ b/xen/arch/x86/srat.c
>> @@ -496,14 +496,21 @@ static unsigned node_to_pxm(nodeid_t n)
>>   	return 0;
>>   }
>>   
>> -int __node_distance(nodeid_t a, nodeid_t b)
>> +u8 __node_distance(nodeid_t a, nodeid_t b)
>>   {
>> -	int index;
>> +	u8 slit_val;
>>   
>>   	if (!acpi_slit)
>>   		return a == b ? 10 : 20;
>> -	index = acpi_slit->locality_count * node_to_pxm(a);
>> -	return acpi_slit->entry[index + node_to_pxm(b)];
>> +
>> +	slit_val = acpi_slit->entry[acpi_slit->locality_count * node_to_pxm(a) +
>> +				                node_to_pxm(b)];
> This would be easier to read if you kept the old index temporary
> (although making it a u64).

Yes.

-boris