Re: [libvirt] [PATCH 2/5] numa: Introduce virDomainNumaNodeDistanceSpecified
On 11/22/2017 04:45 AM, Michal Privoznik wrote:
On 11/22/2017 12:38 AM, John Ferlan wrote:
>
>
> On 11/14/2017 09:47 AM, Michal Privoznik wrote:
>> The function returns true/false depending on distance
>> configuration being present in the domain XML.
>>
>> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
>> ---
>> src/conf/numa_conf.c | 13 +++++++++++++
>> src/conf/numa_conf.h | 4 ++++
>> src/libvirt_private.syms | 1 +
>> 3 files changed, 18 insertions(+)
>>
>> diff --git a/src/conf/numa_conf.c b/src/conf/numa_conf.c
>> index 5f0b3f9ed..6a42777e2 100644
>> --- a/src/conf/numa_conf.c
>> +++ b/src/conf/numa_conf.c
>> @@ -1137,6 +1137,19 @@ virDomainNumaSetNodeCount(virDomainNumaPtr numa, size_t
nmem_nodes)
>> return numa->nmem_nodes;
>> }
>>
>
> Two blank lines here too.
>
>> +bool
>> +virDomainNumaNodeDistanceSpecified(virDomainNumaPtr numa,
>> + size_t node,
>> + size_t sibling)
>> +{
>> + return node < numa->nmem_nodes &&
>> + sibling < numa->nmem_nodes &&
>> + numa->mem_nodes[node].distances &&
>> + numa->mem_nodes[node].distances[sibling].value != LOCAL_DISTANCE
&&
>> + numa->mem_nodes[node].distances[sibling].value != REMOTE_DISTANCE;
>> +}
>> +
>> +
>
> According to how I read commit message '74119a03' it *is* possible to
> set the @value to the same value as LOCAL_DISTANCE(10) or
> REMOTE_DISTANCE(20) - so using that as a comparison for whether it was
> specified would seem to be wrong.
Sure it is possible. But see my reply to 4/5 why I need this function.
>
> Still if a distance *is* provided, then it seems that 'id' and
'value'
> are also required to be provided or defaulted. That means what seems to
> matter regarding whether something was provided is if the *.value and/or
> "*.cellid are zero
>
> At least that's how I'm reading virDomainNumaDefNodeDistanceParseXML
Okay, so the name is confusing. Would you be okay if I rename this to
virDomainNumaNodeDistanceSpecifiedAndNotDefault()? Ugrh, long name. Any
suggestion is welcome.
Sometimes comments to the function that state what it's returning help -
especially the long single boolean condition.
Just remember, naming is hard! How about
virDomainNumaNodeDistanceIsUsingDefaults? The prefix
virDomainNumaNodeDistance makes names longer too...
Not sure I was as hung up over the name as I was the functionality that
at this point in time didn't make as much sense. Although paired with
your comments in patch 4, perhaps make more sense.
I'm also not a fan of the large single condition for the bool function -
especially where some conditions are positive and some are negative, but
that probably just me... If I try to decompose it...
/* Out of range, not created, or not supplied */
if (node >= numa->nmem_nodes || sibling >= numa->nmem_nodes ||
!numa->mem_nodes[node].distances ||
numa->mem_nodes[node].distances[sibling].value == 0)
return false;
/* Supplied using default distances */
if (numa->mem_nodes[node].distances[sibling].value == LOCAL_DISTANCE ||
numa->mem_nodes[node].distances[sibling].value == REMOTE_DISTANCE)
return true;
return false;
Alternatively, I can move LOCAL/REMOTE_DISTANCE macros to numa_conf.h,
give them proper prefix and call virDomainNumaGetNodeDistance() from
qemu and check if returned value is LOCAL/REMOTE.
Hiding comparisons behind some other function that requires me to jump
elsewhere which can be painful too.
John