This came up during patch review of the autofs patches. It's not clear whether this enhancement can make 1.8 beta, so I'm filing it as a ticket.

Stephen said:

Why don't we just store the result data in the "struct automtent" when we complete the _sss_setautomntent() routine? Granted, we'd be carrying around
more memory in autofs, but it would be accessible quite a bit faster than going back and forth to the responder for multiple _sss_getautomntbyname_r()
calls. At the very minimum, it would be better to replicate what we're
doing in the NSS passwd client, where we get SSS_NSS_MAX_ENTRIES at a
time. I can see this being a bottleneck for a system looking up user home
directories for thousands of users.

Additional comment about this. It's not sufficient to have the
endautomntent() value not go to the responder. If the responder is
allocating memory and maintaining a view of the data for this request
series, we need to be able to tell it to release it when we're done.

(The responder will also need to implement a timer event to free memory
after a certain amount of time, so we don't have a memory leak problem
if the calling function doesn't invoke endautomntent())