"clients-per-query" vs "max-clients-per-query"

[Evan Hunt]

On Sat, Jun 07, 2014 at 12:02:24PM -0400, Jorge Fábregas wrote:
> For me, this "clients-per-query" of 10 is an upper limit (maximum number
> of clients before it starts dropping).  So then, what's the purpose of
> "max-clients-per-query"?

Over time, as it runs, named tries to self-tune the clients-per-query
value.

If you set clients-per-query to 10 and max-clients-per-query to 100
(i.e., the default values), that means that the initial limit will be
10, but if we ever actually hit the limit and drop a query, we try
adjusting the limit up to 15, then 20, and so on, until we can keep
up with the queries *or* until we reach 100.

Once we get to a point where we're not spilling queries anymore, we
start experimentally adjusting the limit back downward -- reducing it
by 1 every 20 minutes, if I recall correctly.

If clients-per-query is 0, that means we don't have a clients-per-query
limit at all.  If max-clients-per-query is 0, that means there's no upper
bound on clients-per-query and it can grow as big as it needs to.

-- 
Evan Hunt -- each at isc.org
Internet Systems Consortium, Inc.