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

[Sasha Khapyorsky]

On Sun, 2007-06-17 at 14:11 +0300, Yevgeny Kliteynik wrote:
> 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

Looks perfect for me.

Sasha