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"
diff --git a/net/dccp/ccids/Makefile b/net/dccp/ccids/Makefile
index 438f20b..cdaefff 100644
--- a/net/dccp/ccids/Makefile
+++ b/net/dccp/ccids/Makefile
@@ -1,9 +1 @@
-obj-$(CONFIG_IP_DCCP_CCID3) += dccp_ccid3.o
-
-dccp_ccid3-y := ccid3.o
-
-obj-$(CONFIG_IP_DCCP_CCID2) += dccp_ccid2.o
-
-dccp_ccid2-y := ccid2.o
-
obj-y += lib/
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index c9ea19a..d235294a 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -768,10 +768,9 @@
}
}
-static struct ccid_operations ccid2 = {
+struct ccid_operations ccid2_ops = {
.ccid_id = DCCPC_CCID2,
.ccid_name = "TCP-like",
- .ccid_owner = THIS_MODULE,
.ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
.ccid_hc_tx_init = ccid2_hc_tx_init,
.ccid_hc_tx_exit = ccid2_hc_tx_exit,
@@ -784,22 +783,5 @@
#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
module_param(ccid2_debug, bool, 0644);
-MODULE_PARM_DESC(ccid2_debug, "Enable debug messages");
+MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages");
#endif
-
-static __init int ccid2_module_init(void)
-{
- return ccid_register(&ccid2);
-}
-module_init(ccid2_module_init);
-
-static __exit void ccid2_module_exit(void)
-{
- ccid_unregister(&ccid2);
-}
-module_exit(ccid2_module_exit);
-
-MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
-MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
-MODULE_LICENSE("GPL");
-MODULE_ALIAS("net-dccp-ccid-2");
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 3b8bd7c..a27b7f4 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -940,10 +940,9 @@
return 0;
}
-static struct ccid_operations ccid3 = {
+struct ccid_operations ccid3_ops = {
.ccid_id = DCCPC_CCID3,
.ccid_name = "TCP-Friendly Rate Control",
- .ccid_owner = THIS_MODULE,
.ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
.ccid_hc_tx_init = ccid3_hc_tx_init,
.ccid_hc_tx_exit = ccid3_hc_tx_exit,
@@ -964,23 +963,5 @@
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
module_param(ccid3_debug, bool, 0644);
-MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
+MODULE_PARM_DESC(ccid3_debug, "Enable CCID-3 debug messages");
#endif
-
-static __init int ccid3_module_init(void)
-{
- return ccid_register(&ccid3);
-}
-module_init(ccid3_module_init);
-
-static __exit void ccid3_module_exit(void)
-{
- ccid_unregister(&ccid3);
-}
-module_exit(ccid3_module_exit);
-
-MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
- "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
-MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
-MODULE_LICENSE("GPL");
-MODULE_ALIAS("net-dccp-ccid-3");
