tcp: TCP_NOTSENT_LOWAT socket option

[karo-tx-linux.git] / Documentation / networking / ip-sysctl.txt

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 10742902146fc1da3ae1c84a94929b42a79e29d0..53cea9bcb14c8a55953b8b6938be537106b6ffea 100644 (file)
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -516,6 +516,19 @@ tcp_wmem - vector of 3 INTEGERs: min, default, max
        this value is ignored.
        Default: between 64K and 4MB, depending on RAM size.
 
+tcp_notsent_lowat - UNSIGNED INTEGER
+       A TCP socket can control the amount of unsent bytes in its write queue,
+       thanks to TCP_NOTSENT_LOWAT socket option. poll()/select()/epoll()
+       reports POLLOUT events if the amount of unsent bytes is below a per
+       socket value, and if the write queue is not full. sendmsg() will
+       also not add new buffers if the limit is hit.
+
+       This global variable controls the amount of unsent data for
+       sockets not using TCP_NOTSENT_LOWAT. For these sockets, a change
+       to the global variable has immediate effect.
+
+       Default: UINT_MAX (0xFFFFFFFF)
+
 tcp_workaround_signed_windows - BOOLEAN
        If set, assume no receipt of a window scaling option means the
        remote TCP is broken and treats the window as a signed quantity.