dccp: Lockless integration of CCID congestion-control plugins
Based on Arnaldo's earlier patch, this patch integrates the standardised
CCID congestion control plugins (CCID-2 and CCID-3) of DCCP with dccp.ko:
* enables a faster connection path by eliminating the need to always go
through the CCID registration lock;
* updates the implementation to use only a single array whose size equals
the number of configured CCIDs instead of the maximum (256);
* since the CCIDs are now fixed array elements, synchronization is no
longer needed, simplifying use and implementation.
CCID-2 is suggested as minimum for a basic DCCP implementation (RFC 4340, 10);
CCID-3 is a standards-track CCID supported by RFC 4342 and RFC 5348.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ccids/Kconfig b/net/dccp/ccids/Kconfig
index 1227594..b30f049 100644
--- a/net/dccp/ccids/Kconfig
+++ b/net/dccp/ccids/Kconfig
@@ -1,80 +1,52 @@
menu "DCCP CCIDs Configuration (EXPERIMENTAL)"
depends on EXPERIMENTAL
-config IP_DCCP_CCID2
- tristate "CCID2 (TCP-Like) (EXPERIMENTAL)"
- def_tristate IP_DCCP
- select IP_DCCP_ACKVEC
- ---help---
- CCID 2, TCP-like Congestion Control, denotes Additive Increase,
- Multiplicative Decrease (AIMD) congestion control with behavior
- modelled directly on TCP, including congestion window, slow start,
- timeouts, and so forth [RFC 2581]. CCID 2 achieves maximum
- bandwidth over the long term, consistent with the use of end-to-end
- congestion control, but halves its congestion window in response to
- each congestion event. This leads to the abrupt rate changes
- typical of TCP. Applications should use CCID 2 if they prefer
- maximum bandwidth utilization to steadiness of rate. This is often
- the case for applications that are not playing their data directly
- to the user. For example, a hypothetical application that
- transferred files over DCCP, using application-level retransmissions
- for lost packets, would prefer CCID 2 to CCID 3. On-line games may
- also prefer CCID 2. See RFC 4341 for further details.
-
- CCID2 is the default CCID used by DCCP.
-
config IP_DCCP_CCID2_DEBUG
- bool "CCID2 debugging messages"
- depends on IP_DCCP_CCID2
- ---help---
- Enable CCID2-specific debugging messages.
+ bool "CCID-2 debugging messages"
+ ---help---
+ Enable CCID-2 specific debugging messages.
- When compiling CCID2 as a module, this debugging output can
- additionally be toggled by setting the ccid2_debug module
- parameter to 0 or 1.
+ The debugging output can additionally be toggled by setting the
+ ccid2_debug parameter to 0 or 1.
- If in doubt, say N.
+ If in doubt, say N.
config IP_DCCP_CCID3
- tristate "CCID3 (TCP-Friendly) (EXPERIMENTAL)"
- def_tristate IP_DCCP
+ bool "CCID-3 (TCP-Friendly) (EXPERIMENTAL)"
+ def_bool y if (IP_DCCP = y || IP_DCCP = m)
select IP_DCCP_TFRC_LIB
---help---
- CCID 3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
+ CCID-3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
rate-controlled congestion control mechanism. TFRC is designed to
be reasonably fair when competing for bandwidth with TCP-like flows,
where a flow is "reasonably fair" if its sending rate is generally
within a factor of two of the sending rate of a TCP flow under the
same conditions. However, TFRC has a much lower variation of
- throughput over time compared with TCP, which makes CCID 3 more
- suitable than CCID 2 for applications such streaming media where a
+ throughput over time compared with TCP, which makes CCID-3 more
+ suitable than CCID-2 for applications such streaming media where a
relatively smooth sending rate is of importance.
- CCID 3 is further described in RFC 4342,
+ CCID-3 is further described in RFC 4342,
http://www.ietf.org/rfc/rfc4342.txt
The TFRC congestion control algorithms were initially described in
- RFC 3448.
+ RFC 5448.
This text was extracted from RFC 4340 (sec. 10.2),
http://www.ietf.org/rfc/rfc4340.txt
-
- To compile this CCID as a module, choose M here: the module will be
- called dccp_ccid3.
- If in doubt, say M.
+ If in doubt, say N.
config IP_DCCP_CCID3_DEBUG
- bool "CCID3 debugging messages"
- depends on IP_DCCP_CCID3
- ---help---
- Enable CCID3-specific debugging messages.
+ bool "CCID-3 debugging messages"
+ depends on IP_DCCP_CCID3
+ ---help---
+ Enable CCID-3 specific debugging messages.
- When compiling CCID3 as a module, this debugging output can
- additionally be toggled by setting the ccid3_debug module
- parameter to 0 or 1.
+ The debugging output can additionally be toggled by setting the
+ ccid3_debug parameter to 0 or 1.
- If in doubt, say N.
+ If in doubt, say N.
config IP_DCCP_CCID3_RTO
int "Use higher bound for nofeedback timer"