[ofa-general] Re: [Query] ib add path record cache

[Sean Hefty]

> But initially this will generate a packet for each path, while sys
> admin knows that path is there and he can hard-code the entries for
> it. Other thing is that why Admin will care about creating such record
> while SA is itself taking care, right?

In your original message you asked about adding 'dummy entries' to the 
cache.  I agree that pre-loading the cache can be useful.  What I still 
am not understanding is the reasoning for adding 'dummy entries'.  By 
'dummy entries', I've been assuming that these are invalid path records, 
but maybe that's not what you meant.

> Another point I want to know is,
> When local_sa_cache module will be inserted? After SM comes up or
> Before SM comes up?

It can occur either way.  There is no restriction.  The cache responds 
to port up and GID in/out of service events to update itself.

> If Its inserted before SM is coming up (I am assuming SM is running on
> some node not on switch) then First Forced schedule_update() is
> waisted, and for the first application presence of cache is
> meaningless. Why not to keep cache effective right from the start?

Pre-loading the cache with path records doesn't guarantee that those 
paths are usable.  If the SM has not come up, then the path records will 
be unusable until the SM configures the subnet, plus there's no 
guarantee that the remote endpoints specified by the paths are running.

The main benefit I see to pre-loading the cache is to avoid SA storms 
when booting a large cluster.

- Sean