Documentation: clarify tcp_{r,w}mem sysctl docs
Fix some of the defaults and attempt to clarify some language.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 2774379..dc04fdd 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -336,7 +336,7 @@
pressure.
Default: 8K
- default: default size of receive buffer used by TCP sockets.
+ default: initial size of receive buffer used by TCP sockets.
This value overrides net.core.rmem_default used by other protocols.
Default: 87380 bytes. This value results in window of 65535 with
default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit
@@ -344,8 +344,10 @@
max: maximal size of receive buffer allowed for automatically
selected receiver buffers for TCP socket. This value does not override
- net.core.rmem_max, "static" selection via SO_RCVBUF does not use this.
- Default: 87380*2 bytes.
+ net.core.rmem_max. Calling setsockopt() with SO_RCVBUF disables
+ automatic tuning of that socket's receive buffer size, in which
+ case this value is ignored.
+ Default: between 87380B and 4MB, depending on RAM size.
tcp_sack - BOOLEAN
Enable select acknowledgments (SACKS).
@@ -419,19 +421,21 @@
Enable window scaling as defined in RFC1323.
tcp_wmem - vector of 3 INTEGERs: min, default, max
- min: Amount of memory reserved for send buffers for TCP socket.
+ min: Amount of memory reserved for send buffers for TCP sockets.
Each TCP socket has rights to use it due to fact of its birth.
Default: 4K
- default: Amount of memory allowed for send buffers for TCP socket
- by default. This value overrides net.core.wmem_default used
- by other protocols, it is usually lower than net.core.wmem_default.
+ default: initial size of send buffer used by TCP sockets. This
+ value overrides net.core.wmem_default used by other protocols.
+ It is usually lower than net.core.wmem_default.
Default: 16K
- max: Maximal amount of memory allowed for automatically selected
- send buffers for TCP socket. This value does not override
- net.core.wmem_max, "static" selection via SO_SNDBUF does not use this.
- Default: 128K
+ max: Maximal amount of memory allowed for automatically tuned
+ send buffers for TCP sockets. This value does not override
+ net.core.wmem_max. Calling setsockopt() with SO_SNDBUF disables
+ automatic tuning of that socket's send buffer size, in which case
+ this value is ignored.
+ Default: between 64K and 4MB, depending on RAM size.
tcp_workaround_signed_windows - BOOLEAN
If set, assume no receipt of a window scaling option means the