[ofa-general] PATCH [0/3] osm: adding root and compute node guid files options for fat-tree

[Yevgeny Kliteynik]

Sasha Khapyorsky wrote:
> On 16:57 Fri 15 Jun     , Hal Rosenstock wrote:
>> On Fri, 2007-06-15 at 16:59, Sasha Khapyorsky wrote:
>>> On 16:39 Fri 15 Jun     , Hal Rosenstock wrote:
>>>> On Thu, 2007-06-14 at 09:45, Sasha Khapyorsky wrote:
>>>>> On 15:36 Thu 14 Jun     , Yevgeny Kliteynik wrote:
>>>>>>  Sasha Khapyorsky wrote:
>>>>>>> Hi Yevgeny,
>>>>>>> On 11:19 Thu 14 Jun     , Yevgeny Kliteynik wrote:
>>>>>>>>  The following three patches are adding root and compute node guid files
>>>>>>>>  options for fat-tree routing,
>>>>>>> Is there any reason to not share root guids file option with up/down?
>>>>>>  There are two new options for fat-tree: roots and compute nodes (CN).
>>>>>>  These two will be very "tightly coupled" and would have more implication
>>>>>>  on the routing than in case of up/dn roots. For instance, having root
>>>>>>  file but not CN file means that the topology doesn't have to be pure 
>>>>>>  fat-tree,
>>>>>>  but all the CAs are considered CNs and have to be on the same level of the 
>>>>>>  tree.
>>>>>>  And there is similar implication of all the combinations of these two 
>>>>>>  options.
>>>>>>
>>>>>>  Because of this coupling I wanted to differentiate these two options from
>>>>>>  the up/dn roots.
>>>>>>
>>>>>>  Thoughts?
>>>>> I still not have strong option about two options against common one.
>>>> Me neither.
>>>>
>>>>> Hypothetically if in some days we will implement routing engine chains
>>>>> (so failed algo will fallback to next in chain and not just to default)
>>>>> separate options could be useful.
>>>> So is this a(nother) reason to keep the roots separate or would that be
>>>> dealt with when the routing fallback strategy changes ?
>>> It is yet hypothetical. Currently I don't see a strong practical reasons
>>> to have two separate root guids file options for up/down and fat-tree,
>>> but guess this is minor and not showstopper.
>> Wouldn't a current practical reason be switching between up/down and fat
>> tree and they each have different roots ? Is that a real scenario ?
> 
> Sure (but guess in many cases selected roots will be same for both
> algos).

I think that selected roots will always be same for both algos.
I can't think of any topology that will require different set of roots
for two algorithms that see the fabric as tree with routes going up and
then down.

> I think this scenario will be handled well with single shared
> option, like:
> 
>   opensm -R ftree --roots-file ftree-roots-file
> 
> , and
> 
>   opensm -R updn --roots-file updn-roots-file

I agree with this.
I will rework the patch and replace the updn_guid_file with root_guid_file,
and add cn_guid_file.

This also means that the OSM command line options -a or --add_guid_file
will be replaced with -O or --root_guid_file, and we will have additional
options for CN file: -C or --cn_guid_file

Sounds OK?

-- Yevgeny
> 
> Sasha
>