Konstantin Demin
8cbaf1dea2
3rd patchs (in alphabetical order): - bbr3 - ntsync5 - openwrt - pf-kernel - xanmod - zen no configuration changes for now
113 lines
3.6 KiB
Diff
113 lines
3.6 KiB
Diff
From 38dd25482f815d949fec91edd7694b2f15823f67 Mon Sep 17 00:00:00 2001
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From: David Morley <morleyd@google.com>
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Date: Fri, 14 Jul 2023 11:07:56 -0400
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Subject: [PATCH 15/19] tcp: introduce per-route feature RTAX_FEATURE_ECN_LOW
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Define and implement a new per-route feature, RTAX_FEATURE_ECN_LOW.
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This feature indicates that the given destination network is a
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low-latency ECN environment, meaning both that ECN CE marks are
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applied by the network using a low-latency marking threshold and also
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that TCP endpoints provide precise per-data-segment ECN feedback in
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ACKs (where the ACK ECE flag echoes the received CE status of all
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newly-acknowledged data segments). This feature indication can be used
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by congestion control algorithms to decide how to interpret ECN
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signals over the given destination network.
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This feature is appropriate for datacenter-style ECN marking, such as
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the ECN marking approach expected by DCTCP or BBR congestion control
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modules.
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Signed-off-by: David Morley <morleyd@google.com>
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Signed-off-by: Neal Cardwell <ncardwell@google.com>
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Signed-off-by: Yuchung Cheng <ycheng@google.com>
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Tested-by: David Morley <morleyd@google.com>
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Change-Id: I6bc06e9c6cb426fbae7243fc71c9a8c18175f5d3
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Signed-off-by: Alexandre Frade <kernel@xanmod.org>
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---
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include/net/tcp.h | 10 ++++++++++
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include/uapi/linux/rtnetlink.h | 4 +++-
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net/ipv4/tcp_minisocks.c | 2 ++
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net/ipv4/tcp_output.c | 6 ++++--
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4 files changed, 19 insertions(+), 3 deletions(-)
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--- a/include/net/tcp.h
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+++ b/include/net/tcp.h
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@@ -375,6 +375,7 @@ static inline void tcp_dec_quickack_mode
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#define TCP_ECN_QUEUE_CWR 2
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#define TCP_ECN_DEMAND_CWR 4
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#define TCP_ECN_SEEN 8
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+#define TCP_ECN_LOW 16
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enum tcp_tw_status {
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TCP_TW_SUCCESS = 0,
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@@ -777,6 +778,15 @@ static inline void tcp_fast_path_check(s
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tcp_fast_path_on(tp);
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}
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+static inline void tcp_set_ecn_low_from_dst(struct sock *sk,
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+ const struct dst_entry *dst)
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+{
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+ struct tcp_sock *tp = tcp_sk(sk);
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+
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+ if (dst_feature(dst, RTAX_FEATURE_ECN_LOW))
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+ tp->ecn_flags |= TCP_ECN_LOW;
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+}
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+
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u32 tcp_delack_max(const struct sock *sk);
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/* Compute the actual rto_min value */
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--- a/include/uapi/linux/rtnetlink.h
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+++ b/include/uapi/linux/rtnetlink.h
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@@ -507,12 +507,14 @@ enum {
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#define RTAX_FEATURE_TIMESTAMP (1 << 2) /* unused */
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#define RTAX_FEATURE_ALLFRAG (1 << 3) /* unused */
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#define RTAX_FEATURE_TCP_USEC_TS (1 << 4)
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+#define RTAX_FEATURE_ECN_LOW (1 << 5)
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#define RTAX_FEATURE_MASK (RTAX_FEATURE_ECN | \
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RTAX_FEATURE_SACK | \
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RTAX_FEATURE_TIMESTAMP | \
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RTAX_FEATURE_ALLFRAG | \
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- RTAX_FEATURE_TCP_USEC_TS)
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+ RTAX_FEATURE_TCP_USEC_TS | \
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+ RTAX_FEATURE_ECN_LOW)
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struct rta_session {
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__u8 proto;
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--- a/net/ipv4/tcp_minisocks.c
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+++ b/net/ipv4/tcp_minisocks.c
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@@ -459,6 +459,8 @@ void tcp_ca_openreq_child(struct sock *s
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u32 ca_key = dst_metric(dst, RTAX_CC_ALGO);
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bool ca_got_dst = false;
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+ tcp_set_ecn_low_from_dst(sk, dst);
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+
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if (ca_key != TCP_CA_UNSPEC) {
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const struct tcp_congestion_ops *ca;
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--- a/net/ipv4/tcp_output.c
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+++ b/net/ipv4/tcp_output.c
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@@ -336,10 +336,9 @@ static void tcp_ecn_send_syn(struct sock
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bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk);
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bool use_ecn = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn) == 1 ||
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tcp_ca_needs_ecn(sk) || bpf_needs_ecn;
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+ const struct dst_entry *dst = __sk_dst_get(sk);
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if (!use_ecn) {
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- const struct dst_entry *dst = __sk_dst_get(sk);
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-
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if (dst && dst_feature(dst, RTAX_FEATURE_ECN))
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use_ecn = true;
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}
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@@ -351,6 +350,9 @@ static void tcp_ecn_send_syn(struct sock
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tp->ecn_flags = TCP_ECN_OK;
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if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn)
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INET_ECN_xmit(sk);
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+
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+ if (dst)
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+ tcp_set_ecn_low_from_dst(sk, dst);
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}
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}
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