[ofa-general] Re: [PATCH] opensm: preserve base lid routes

[Hal Rosenstock]

On Thu, 2008-06-12 at 14:22 +0300, Olga Shern (Voltaire) wrote:
> 
> 
> On 6/12/08, Olga Shern (Voltaire) <olga.shern at gmail.com> wrote: 
>         
>         
>         On 6/12/08, Hal Rosenstock <hrosenstock at xsigo.com> wrote: 
>                 On Tue, 2008-06-10 at 05:59 +0300, Sasha Khapyorsky
>                 wrote:
>                 > Basically this addresses the problem described by Al
>                 Chu in:
>                 >
>                 > http://lists.openfabrics.org/pipermail/general/2008-
>                 April/049132.html
>                 >
>                 > When base lid paths become completely disbalanced on
>                 a fabrics with
>                 > lmc > 0.
>                 >
>                 > One feedback was from Yiftah Shahar:
>                 >
>                 > "I think that our requirements should be that even
>                 when you are working
>                 > with LMC>0 then the base LID routing should not be
>                 affected.
>                 
>                 > One way to achieve this goal is to first run the
>                 base-LID routing (so
>                 > all base LID improvement will be also in LMC>0) and
>                 then start with the
>                 > other LIDs as round-robbing starting from the base-
>                 lid-port + 1
>                 > according current routing algorithm rules (keeping
>                 min-hop, up/down...)."
>                 >
>                 > We had some discussion with Al and Yiftah about this
>                 and considered that
>                 > in addition to "pure" base lid paths preservation
>                 (which is good thing by
>                 > itself) proposed method solves original lid
>                 disbalancing problem as well.
>                 
>                 Would you elaborate on the motivation behind the
>                 requirement to
>                 maintain/preserve the base LID routing ?
>                 
>                 -- Hal
>          
>         LMC > 0 is mainly used by MPI, all other protocols /
>         applications will use only one LID (PATH),

That's today; what happens when more ULPs are able to take advantage of
alternate LIDs ?

-- Hal

>           therefore we should make sure that performance of these
>         protocols / applications will not be effected if fabric is
>         configured with LMC > 0  
>  
>  
> I meant "affected" and not "effected" of course 
> 
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