Document queue-limit in performance.rst as promised.

settings.rst tells the reader to also see performance.rst regarding
queue-limit but there's nothing there, until now.

diff --git a/docs/performance.rst b/docs/performance.rst
index 610b8965f6788f7dae14dd77aa0df2e2718228b0..8c44ef24663f9a23d0cc778146806d24c947dd24 100644 (file)
--- a/docs/performance.rst
+++ b/docs/performance.rst
@@ -63,6 +63,10 @@ the value of the :ref:`stat-qsize-q` variable. This represents the number of
 packets waiting for database attention. During normal operations the
 queue should be small.
 
+The value of :ref:`setting-queue-limit` should be set to only keep queries in
+queue for as long as someone would be interested in knowing the answer. Many
+resolvers will query other name servers for the zone quite aggressively.
+
 Logging truly kills performance as answering a question from the cache
 is an order of magnitude less work than logging a line about it. Busy
 sites will prefer to turn :ref:`setting-log-dns-details` off.