clarify buffer size options

the documentation for {udp,tcp}-{send,receive}-buffer options
was not complete. also revised for grammar.

diff --git a/doc/arm/reference.rst b/doc/arm/reference.rst
index 073ec17cd737e6e3d83e0645f4c59e0113c51fa8..e8c348846c2095f33ac7f2c7f61d7698006f77da 100644 (file)
--- a/doc/arm/reference.rst
+++ b/doc/arm/reference.rst
@@ -3586,22 +3586,26 @@ Tuning
    milliseconds.
 
 ``tcp-recv-buffer``;  ``udp-recv-buffer``
-   These options control the operating system receiving network buffer sizes for
-   TCP and UDP respectively.  Buffering on the operating system level can
-   prevent packet drops during short spikes, but if the value is set too large
-   it could clog up a running server with outstanding queries that have already
-   timeouted. The default is ``0`` which means to use the operating system
-   default value.  The operating system caps the maximum value that the user can
-   set here.
+   These options control the operating system's receive buffer sizes
+   (``SO_RCVBUF``) for TCP and UDP sockets respectively.  Buffering at
+   the operating system level can prevent packet drops during brief load
+   spikes, but if the value is set too high, it could clog a running server
+   with outstanding queries that have already timed out. The default is
+   ``0``, which means the operating system's default value should be used.
+   The minimum configurable value is ``4096``; any nonzero value lower than
+   that will be silently raised. The maximum value is determined by the
+   kernel, and values exceeding the maximum will be silently reduced.
 
 ``tcp-send-buffer``; ``udp-send-buffer``
-   These options control the operating system sending network buffer sizes for
-   TCP and UDP respectively.  Buffering on the operating system level can
-   prevent packet drops during short spikes, but if the value is set too large
-   it could clog up a running server with outstanding queries that have already
-   timeouted. The default is ``0`` which means to use the operating system
-   default value.  The operating system caps the maximum value that the user can
-   set here.
+   These options control the operating system's send buffer sizes
+   (``SO_SNDBUF``) for TCP and UDP sockets respectively.  Buffering at the
+   operating system level can prevent packet drops during brief load
+   spikes, but if the value is set too high, it could clog a running server
+   with outstanding queries that have already timed out. The default is
+   ``0``, which means the operating system's default value should be used.
+   The minimum configurable value is ``4096``; any nonzero value lower than
+   that will be silently raised. The maximum value is determined by the
+   kernel, and values exceeding the maximum will be silently reduced.
 
 .. _builtin: