diff --git a/doc/configuration.txt b/doc/configuration.txt
index 78439aab2..de7384bfc 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -693,6 +693,8 @@ The following keywords are supported in the "global" section :
    - tune.maxrewrite
    - tune.pattern.cache-size
    - tune.pipesize
+   - tune.pool-high-fd-ratio
+   - tune.pool-low-fd-ratio
    - tune.rcvbuf.client
    - tune.rcvbuf.server
    - tune.recv_enough