[UDP]: Add memory accounting.

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

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 32c2e9da5f3a3dd0f2c522799ffa92575f64a01e..17a6e46fbd43abfce8ad5558f99200f8389ac650 100644 (file)
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -180,13 +180,20 @@ tcp_fin_timeout - INTEGER
        to live longer. Cf. tcp_max_orphans.
 
 tcp_frto - INTEGER
-       Enables F-RTO, an enhanced recovery algorithm for TCP retransmission
+       Enables Forward RTO-Recovery (F-RTO) defined in RFC4138.
+       F-RTO is an enhanced recovery algorithm for TCP retransmission
        timeouts.  It is particularly beneficial in wireless environments
        where packet loss is typically due to random radio interference
-       rather than intermediate router congestion. If set to 1, basic
-       version is enabled. 2 enables SACK enhanced F-RTO, which is
-       EXPERIMENTAL. The basic version can be used also when SACK is
-       enabled for a flow through tcp_sack sysctl.
+       rather than intermediate router congestion.  F-RTO is sender-side
+       only modification.  Therefore it does not require any support from
+       the peer, but in a typical case, however, where wireless link is
+       the local access link and most of the data flows downlink, the
+       faraway servers should have F-RTO enabled to take advantage of it.
+       If set to 1, basic version is enabled.  2 enables SACK enhanced
+       F-RTO if flow uses SACK.  The basic version can be used also when
+       SACK is in use though scenario(s) with it exists where F-RTO
+       interacts badly with the packet counting of the SACK enabled TCP
+       flow.
 
 tcp_frto_response - INTEGER
        When F-RTO has detected that a TCP retransmission timeout was
@@ -286,7 +293,7 @@ tcp_no_metrics_save - BOOLEAN
        when the connection closes, so that connections established in the
        near future can use these to set initial conditions.  Usually, this
        increases overall performance, but may sometimes cause performance
-       degredation.  If set, TCP will not cache metrics on closing
+       degradation.  If set, TCP will not cache metrics on closing
        connections.
 
 tcp_orphan_retries - INTEGER
@@ -439,6 +446,33 @@ tcp_dma_copybreak - INTEGER
        and CONFIG_NET_DMA is enabled.
        Default: 4096
 
+UDP variables:
+
+udp_mem - vector of 3 INTEGERs: min, pressure, max
+       Number of pages allowed for queueing by all UDP sockets.
+
+       min: Below this number of pages UDP is not bothered about its
+       memory appetite. When amount of memory allocated by UDP exceeds
+       this number, UDP starts to moderate memory usage.
+
+       pressure: This value was introduced to follow format of tcp_mem.
+
+       max: Number of pages allowed for queueing by all UDP sockets.
+
+       Default is calculated at boot time from amount of available memory.
+
+udp_rmem_min - INTEGER
+       Minimal size of receive buffer used by UDP sockets in moderation.
+       Each UDP socket is able to use the size for receiving data, even if
+       total pages of UDP sockets exceed udp_mem pressure. The unit is byte.
+       Default: 4096
+
+udp_wmem_min - INTEGER
+       Minimal size of send buffer used by UDP sockets in moderation.
+       Each UDP socket is able to use the size for sending data, even if
+       total pages of UDP sockets exceed udp_mem pressure. The unit is byte.
+       Default: 4096
+
 CIPSOv4 Variables:
 
 cipso_cache_enable - BOOLEAN