[openib-general] SA cache design

[Rimmer, Todd]

> From: Hal Rosenstock [mailto:halr at voltaire.com]
> On Thu, 2006-01-05 at 18:36, Rimmer, Todd wrote:
> > This of course implies the "SA Mux" must analyze more than just 
> > the attribute ID to determine if the replica can handle the query.  
> > But the memory savings is well worth the extra level of filtering.
> 
> If the SA cache does this, it seems it would be pretty simple 
> to return
> this info in an attribute to the client so the client would 
> know when to
> go to the cache/replica and when to go direct to the SA in the case
> where only certain queries are supported. Wouldn't this be 
> advantageous
> when the replica doesn't support all queries ?

Why put the burden on the application.  give the query to the Mux.  With an optional flag indicating a prefered "routing" (choices of: to SA, to replica, let Mux decide).  Then let it decide.  As you suggest it may be simplest to let the Mux try the replica and on failure fallback to the SA transparent to the app (sort of the way SDP intercepts socket ops and falls back to TCP/IP when SDP isn't appropriate).

Todd R.