af_rxrpc: Add sysctls for configuring RxRPC parameters
Add sysctls for configuring RxRPC protocol handling, specifically controls on
delays before ack generation, the delay before resending a packet, the maximum
lifetime of a call and the expiration times of calls, connections and
transports that haven't been recently used.
More info added in Documentation/networking/rxrpc.txt.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/Documentation/networking/rxrpc.txt b/Documentation/networking/rxrpc.txt
index b89bc82e..aa08d26 100644
--- a/Documentation/networking/rxrpc.txt
+++ b/Documentation/networking/rxrpc.txt
@@ -27,6 +27,8 @@
(*) AF_RXRPC kernel interface.
+ (*) Configurable parameters.
+
========
OVERVIEW
@@ -864,3 +866,63 @@
This is used to allocate a null RxRPC key that can be used to indicate
anonymous security for a particular domain.
+
+
+=======================
+CONFIGURABLE PARAMETERS
+=======================
+
+The RxRPC protocol driver has a number of configurable parameters that can be
+adjusted through sysctls in /proc/net/rxrpc/:
+
+ (*) req_ack_delay
+
+ The amount of time in milliseconds after receiving a packet with the
+ request-ack flag set before we honour the flag and actually send the
+ requested ack.
+
+ Usually the other side won't stop sending packets until the advertised
+ reception window is full (to a maximum of 255 packets), so delaying the
+ ACK permits several packets to be ACK'd in one go.
+
+ (*) soft_ack_delay
+
+ The amount of time in milliseconds after receiving a new packet before we
+ generate a soft-ACK to tell the sender that it doesn't need to resend.
+
+ (*) idle_ack_delay
+
+ The amount of time in milliseconds after all the packets currently in the
+ received queue have been consumed before we generate a hard-ACK to tell
+ the sender it can free its buffers, assuming no other reason occurs that
+ we would send an ACK.
+
+ (*) resend_timeout
+
+ The amount of time in milliseconds after transmitting a packet before we
+ transmit it again, assuming no ACK is received from the receiver telling
+ us they got it.
+
+ (*) max_call_lifetime
+
+ The maximum amount of time in seconds that a call may be in progress
+ before we preemptively kill it.
+
+ (*) dead_call_expiry
+
+ The amount of time in seconds before we remove a dead call from the call
+ list. Dead calls are kept around for a little while for the purpose of
+ repeating ACK and ABORT packets.
+
+ (*) connection_expiry
+
+ The amount of time in seconds after a connection was last used before we
+ remove it from the connection list. Whilst a connection is in existence,
+ it serves as a placeholder for negotiated security; when it is deleted,
+ the security must be renegotiated.
+
+ (*) transport_expiry
+
+ The amount of time in seconds after a transport was last used before we
+ remove it from the transport list. Whilst a transport is in existence, it
+ serves to anchor the peer data and keeps the connection ID counter.