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

[Yevgeny Kliteynik]

Yevgeny Kliteynik wrote:
> 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

Sorry, -C is already taken. I'm running out of letters here... :)
Suggesting leaving 'a' for roots, and using 'u' for CNs:

  -a or --root_guid_file
  -u or --cn_guid_file

-- Yevgeny

> Sounds OK?
> 
> -- Yevgeny
>>
>> Sasha
>>
> 
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