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| author | Daniel Borkmann <daniel@iogearbox.net> | 2015-08-31 15:58:47 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-08-31 12:34:00 -0700 |
| commit | c3a8d9474684d391b0afc3970d9b249add15ec07 (patch) | |
| tree | f12130b61955f4471ebd61474244ecf9ebdc0858 /include/net/tcp.h | |
| parent | b8d3e4163a3562d7cba486687904383e78e7dd6a (diff) | |
| download | lwn-c3a8d9474684d391b0afc3970d9b249add15ec07.tar.gz lwn-c3a8d9474684d391b0afc3970d9b249add15ec07.zip | |
tcp: use dctcp if enabled on the route to the initiator
Currently, the following case doesn't use DCTCP, even if it should:
A responder has f.e. Cubic as system wide default, but for a specific
route to the initiating host, DCTCP is being set in RTAX_CC_ALGO. The
initiating host then uses DCTCP as congestion control, but since the
initiator sets ECT(0), tcp_ecn_create_request() doesn't set ecn_ok,
and we have to fall back to Reno after 3WHS completes.
We were thinking on how to solve this in a minimal, non-intrusive
way without bloating tcp_ecn_create_request() needlessly: lets cache
the CA ecn option flag in RTAX_FEATURES. In other words, when ECT(0)
is set on the SYN packet, set ecn_ok=1 iff route RTAX_FEATURES
contains the unexposed (internal-only) DST_FEATURE_ECN_CA. This allows
to only do a single metric feature lookup inside tcp_ecn_create_request().
Joint work with Florian Westphal.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/tcp.h')
| -rw-r--r-- | include/net/tcp.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index 4a7b03947a38..0cab28cd43a9 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -888,7 +888,7 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); extern struct tcp_congestion_ops tcp_reno; struct tcp_congestion_ops *tcp_ca_find_key(u32 key); -u32 tcp_ca_get_key_by_name(const char *name); +u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); #ifdef CONFIG_INET char *tcp_ca_get_name_by_key(u32 key, char *buffer); #else |