-----Original Message----- From: Eric Dumazet edumazet@google.com Sent: Wednesday, June 25, 2025 11:21 AM To: Chia-Yu Chang (Nokia) chia-yu.chang@nokia-bell-labs.com Cc: pabeni@redhat.com; linux-doc@vger.kernel.org; corbet@lwn.net; horms@kernel.org; dsahern@kernel.org; kuniyu@amazon.com; bpf@vger.kernel.org; netdev@vger.kernel.org; dave.taht@gmail.com; jhs@mojatatu.com; kuba@kernel.org; stephen@networkplumber.org; xiyou.wangcong@gmail.com; jiri@resnulli.us; davem@davemloft.net; andrew+netdev@lunn.ch; donald.hunter@gmail.com; ast@fiberby.net; liuhangbin@gmail.com; shuah@kernel.org; linux-kselftest@vger.kernel.org; ij@kernel.org; ncardwell@google.com; Koen De Schepper (Nokia) koen.de_schepper@nokia-bell-labs.com; g.white@cablelabs.com; ingemar.s.johansson@ericsson.com; mirja.kuehlewind@ericsson.com; cheshire@apple.com; rs.ietf@gmx.at; Jason_Livingood@comcast.com; vidhi_goel@apple.com Subject: Re: [PATCH v9 net-next 09/15] tcp: accecn: AccECN option
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On Sat, Jun 21, 2025 at 12:38 PM chia-yu.chang@nokia-bell-labs.com wrote:
From: Ilpo Järvinen ij@kernel.org
[...]
--- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -316,6 +316,13 @@ struct tcp_info { * in milliseconds, including any * unfinished recovery. */
__u32 tcpi_received_ce; /* # of CE marks received */__u32 tcpi_delivered_e1_bytes; /* Accurate ECN byte counters */__u32 tcpi_delivered_e0_bytes;__u32 tcpi_delivered_ce_bytes;__u32 tcpi_received_e1_bytes;__u32 tcpi_received_e0_bytes;__u32 tcpi_received_ce_bytes;We need to immediately fill the 32bit hole, otherwise we won't be able to use it in the future.
Hi Eric,
I did not see any holes created after adding these __u32 values, and you can see the pahole result of tcp_info below:
And the pahole result is the same either I compile with ARM32 or 64-bit architecture.
Or you mean we need an extra "__u32 unused;" at the end?
struct tcp_info { __u8 tcpi_state; /* 0 1 */ __u8 tcpi_ca_state; /* 1 1 */ __u8 tcpi_retransmits; /* 2 1 */ __u8 tcpi_probes; /* 3 1 */ __u8 tcpi_backoff; /* 4 1 */ __u8 tcpi_options; /* 5 1 */ __u8 tcpi_snd_wscale:4; /* 6: 0 1 */ __u8 tcpi_rcv_wscale:4; /* 6: 4 1 */ __u8 tcpi_delivery_rate_app_limited:1; /* 7: 0 1 */ __u8 tcpi_fastopen_client_fail:2; /* 7: 1 1 */
/* XXX 5 bits hole, try to pack */
__u32 tcpi_rto; /* 8 4 */ __u32 tcpi_ato; /* 12 4 */ __u32 tcpi_snd_mss; /* 16 4 */ __u32 tcpi_rcv_mss; /* 20 4 */ __u32 tcpi_unacked; /* 24 4 */ __u32 tcpi_sacked; /* 28 4 */ __u32 tcpi_lost; /* 32 4 */ __u32 tcpi_retrans; /* 36 4 */ __u32 tcpi_fackets; /* 40 4 */ __u32 tcpi_last_data_sent; /* 44 4 */ __u32 tcpi_last_ack_sent; /* 48 4 */ __u32 tcpi_last_data_recv; /* 52 4 */ __u32 tcpi_last_ack_recv; /* 56 4 */ __u32 tcpi_pmtu; /* 60 4 */ /* --- cacheline 1 boundary (64 bytes) --- */ __u32 tcpi_rcv_ssthresh; /* 64 4 */ __u32 tcpi_rtt; /* 68 4 */ __u32 tcpi_rttvar; /* 72 4 */ __u32 tcpi_snd_ssthresh; /* 76 4 */ __u32 tcpi_snd_cwnd; /* 80 4 */ __u32 tcpi_advmss; /* 84 4 */ __u32 tcpi_reordering; /* 88 4 */ __u32 tcpi_rcv_rtt; /* 92 4 */ __u32 tcpi_rcv_space; /* 96 4 */ __u32 tcpi_total_retrans; /* 100 4 */ __u64 tcpi_pacing_rate; /* 104 8 */ __u64 tcpi_max_pacing_rate; /* 112 8 */ __u64 tcpi_bytes_acked; /* 120 8 */ /* --- cacheline 2 boundary (128 bytes) --- */ __u64 tcpi_bytes_received; /* 128 8 */ __u32 tcpi_segs_out; /* 136 4 */ __u32 tcpi_segs_in; /* 140 4 */ __u32 tcpi_notsent_bytes; /* 144 4 */ __u32 tcpi_min_rtt; /* 148 4 */ __u32 tcpi_data_segs_in; /* 152 4 */ __u32 tcpi_data_segs_out; /* 156 4 */ __u64 tcpi_delivery_rate; /* 160 8 */ __u64 tcpi_busy_time; /* 168 8 */ __u64 tcpi_rwnd_limited; /* 176 8 */ __u64 tcpi_sndbuf_limited; /* 184 8 */ /* --- cacheline 3 boundary (192 bytes) --- */ __u32 tcpi_delivered; /* 192 4 */ __u32 tcpi_delivered_ce; /* 196 4 */ __u64 tcpi_bytes_sent; /* 200 8 */ __u64 tcpi_bytes_retrans; /* 208 8 */ __u32 tcpi_dsack_dups; /* 216 4 */ __u32 tcpi_reord_seen; /* 220 4 */ __u32 tcpi_rcv_ooopack; /* 224 4 */ __u32 tcpi_snd_wnd; /* 228 4 */ __u32 tcpi_rcv_wnd; /* 232 4 */ __u32 tcpi_rehash; /* 236 4 */ __u16 tcpi_total_rto; /* 240 2 */ __u16 tcpi_total_rto_recoveries; /* 242 2 */ __u32 tcpi_total_rto_time; /* 244 4 */ __u32 tcpi_received_ce; /* 248 4 */ __u32 tcpi_delivered_e1_bytes; /* 252 4 */ /* --- cacheline 4 boundary (256 bytes) --- */ __u32 tcpi_delivered_e0_bytes; /* 256 4 */ __u32 tcpi_delivered_ce_bytes; /* 260 4 */ __u32 tcpi_received_e1_bytes; /* 264 4 */ __u32 tcpi_received_e0_bytes; /* 268 4 */ __u32 tcpi_received_ce_bytes; /* 272 4 */
/* size: 280, cachelines: 5, members: 68 */ /* sum members: 274 */ /* sum bitfield members: 11 bits, bit holes: 1, sum bit holes: 5 bits */ /* padding: 4 */ /* last cacheline: 24 bytes */ };
[...]
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index a327fc14b207..66390966cc41 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -70,6 +70,7 @@ #include <linux/sysctl.h> #include <linux/kernel.h> #include <linux/prefetch.h> +#include <linux/bitops.h> #include <net/dst.h> #include <net/tcp.h> #include <net/proto_memory.h> @@ -530,6 +531,139 @@ static bool tcp_ecn_rcv_ecn_echo(const struct tcp_sock *tp, const struct tcphdr return false; }
+/* Maps IP ECN field ECT/CE code point to AccECN option field number, +given
- we are sending fields with Accurate ECN Order 1: ECT(1), CE, ECT(0).
- */
+static u8 tcp_ecnfield_to_accecn_optfield(u8 ecnfield) {
switch (ecnfield & INET_ECN_MASK) {case INET_ECN_NOT_ECT:return 0; /* AccECN does not send counts of NOT_ECT */case INET_ECN_ECT_1:return 1;case INET_ECN_CE:return 2;case INET_ECN_ECT_0:return 3;}return 0;+}
net/ipv4/tcp_input.c has already 7273 lines....
I would suggest adding all these tcp ecn helpers in a separate include file, and move existing ones.
Sure, I will create another header file including tcp ecn & accecn helpers.
Chia-Yu