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sctp: Allow to disable SCTP checksums via module parameter

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This is a new version of my patch, now using a module parameter instead
of a sysctl, so that the option is harder to find. Please note that,
once the module is loaded, it is still possible to change the value of
the parameter in /sys/module/sctp/parameters/, which is useful if you
want to do performance comparisons without rebooting.

Computation of SCTP checksums significantly affects the performance of
SCTP. For example, using two dual-Opteron 246 connected using a Gbe
network, it was not possible to achieve more than ~730 Mbps, compared to
941 Mbps after disabling SCTP checksums.
Unfortunately, SCTP checksum offloading in NICs is not commonly
available (yet).

By default, checksums are still enabled, of course.

Signed-off-by: Lucas Nussbaum <lucas.nussbaum@ens-lyon.fr>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Lucas Nussbaum 2009-02-13 08:33:41 +00:00 committed by David S. Miller
parent 85e8d004ec
commit 06e868066e
4 changed files with 10 additions and 2 deletions
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5
include/net/sctp/structs.h
View file

@ -218,6 +218,10 @@ extern struct sctp_globals {
/* Flag to idicate if SCTP-AUTH is enabled */
int auth_enable;
/* Flag to indicate whether computing and verifying checksum
* is disabled. */
int checksum_disable;
} sctp_globals;
#define sctp_rto_initial (sctp_globals.rto_initial)
@ -252,6 +256,7 @@ extern struct sctp_globals {
#define sctp_addip_noauth (sctp_globals.addip_noauth_enable)
#define sctp_prsctp_enable (sctp_globals.prsctp_enable)
#define sctp_auth_enable (sctp_globals.auth_enable)
#define sctp_checksum_disable (sctp_globals.checksum_disable)
/* SCTP Socket type: UDP or TCP style. */
typedef enum {

3
net/sctp/input.c
View file

@ -142,7 +142,8 @@ int sctp_rcv(struct sk_buff *skb)
__skb_pull(skb, skb_transport_offset(skb));
if (skb->len < sizeof(struct sctphdr))
goto discard_it;
if (!skb_csum_unnecessary(skb) && sctp_rcv_checksum(skb) < 0)
if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
sctp_rcv_checksum(skb) < 0)
goto discard_it;
skb_pull(skb, sizeof(struct sctphdr));

2
net/sctp/output.c
View file

@ -531,7 +531,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
* Note: Adler-32 is no longer applicable, as has been replaced
* by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
*/
if (!(dst->dev->features & NETIF_F_NO_CSUM)) {
if (!sctp_checksum_disable && !(dst->dev->features & NETIF_F_NO_CSUM)) {
crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);
crc32 = sctp_end_cksum(crc32);
} else

2
net/sctp/protocol.c
View file

@ -1411,4 +1411,6 @@ MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-132");
MODULE_ALIAS("net-pf-" __stringify(PF_INET6) "-proto-132");
MODULE_AUTHOR("Linux Kernel SCTP developers <lksctp-developers@lists.sourceforge.net>");
MODULE_DESCRIPTION("Support for the SCTP protocol (RFC2960)");
module_param_named(no_checksums, sctp_checksum_disable, bool, 0644);
MODULE_PARM_DESC(no_checksums, "Disable checksums computing and verification");
MODULE_LICENSE("GPL");