[ofa-general] Re: [PATCH] ib/ipoib: Reduce comparison size in data path

[Hal Rosenstock]

On Wed, 2008-01-02 at 10:16 -0800, Roland Dreier wrote:
>  > In the majority of cases, if the neighbour will change, it will
>  > be reflected in the guid part of the GID (bytes 8-15). If the GID
>  > prefix will change as well (bytes 0-7) it will be because the master
>  > SM has changed, in which case we will get an SM change event resulting
>  > in all paths flushed.
> 
> Is it guaranteed that an active SM can't change a GID prefix?

I think that is left as an exercise left to the IBA spec reader as to 
changing GID prefix (in PortInfo). This would be part of Change
Management which was punted by the IBTA.

> Especially if we're using a GID at an index != 0?

Do you mean GUID ?

-- Hal

> In other words, is this change definitely 100 percent safe?
> 
> Also I assume this change is coming from performance tuning.  For
> patches like this it is always helpful to include hard data like "this
> gives a speedup of X on test Y on system Z."
> 
> Thanks...
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