> -----Original Message-----
> From: Eric Dumazet <eduma...@google.com>
> Sent: Wednesday, June 25, 2025 11:21 AM
> To: Chia-Yu Chang (Nokia) <chia-yu.ch...@nokia-bell-labs.com>
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> 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.ch...@nokia-bell-labs.com> wrote:
> >
> > From: Ilpo Järvinen <i...@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
