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dccp: Lockless integration of CCID congestion-control plugins

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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>
This commit is contained in:
Gerrit Renker
2009-01-04 21:42:53 -08:00
committed by David S. Miller
parent 6ea2fde13a
commit ddebc973c5
11 changed files with 148 additions and 168 deletions
Download Patch File Download Diff File Expand all files Collapse all files

70
net/dccp/ccids/Kconfig
View File

@@ -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"

8
net/dccp/ccids/Makefile
View File

@@ -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/

22
net/dccp/ccids/ccid2.c
View File

@@ -768,10 +768,9 @@ static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
}
}
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 @@ static struct ccid_operations ccid2 = {
#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");

23
net/dccp/ccids/ccid3.c
View File

@@ -940,10 +940,9 @@ static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
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 @@ static struct ccid_operations ccid3 = {
#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");