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Message-ID: <CADVnQymW05vi9nj3FBUEwCsZcqkEihXoMQrG7Oa-21Rv36Z9_Q@mail.gmail.com>
Date: Fri, 20 Oct 2023 14:41:42 -0400
From: Neal Cardwell <ncardwell@...gle.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
Yuchung Cheng <ycheng@...gle.com>, Kevin Yang <yyd@...gle.com>,
Soheil Hassas Yeganeh <soheil@...gle.com>, Wei Wang <weiwan@...gle.com>, Van Jacobson <vanj@...gle.com>,
Florian Westphal <fw@...len.de>, eric.dumazet@...il.com
Subject: Re: [PATCH net-next 00/13] tcp: add optional usec resolution to TCP TS
On Fri, Oct 20, 2023 at 8:57 AM Eric Dumazet <edumazet@...gle.com> wrote:
>
> As discussed in various public places in 2016, Google adopted
> usec resolution in RFC 7323 TS values, at Van Jacobson suggestion.
>
> Goals were :
>
> 1) better observability of delays in networking stacks/fabrics.
>
> 2) better disambiguation of events based on TSval/ecr values.
>
> 3) building block for congestion control modules needing usec resolution.
>
> Back then we implemented a schem based on private SYN options
> to safely negotiate the feature.
>
> For upstream submission, we chose to use a much simpler route
> attribute because this feature is probably going to be used
> in private networks.
>
> ip route add 10/8 ... features tcp_usec_ts
>
> References:
>
> https://www.ietf.org/proceedings/97/slides/slides-97-tcpm-tcp-options-for-low-latency-00.pdf
> https://datatracker.ietf.org/doc/draft-wang-tcpm-low-latency-opt/
>
> First two patches are fixing old minor bugs and might be taken
> by stable teams (thanks to appropriate Fixes: tags)
>
> Eric Dumazet (13):
> chtls: fix tp->rcv_tstamp initialization
> tcp: fix cookie_init_timestamp() overflows
> tcp: add tcp_time_stamp_ms() helper
> tcp: introduce tcp_clock_ms()
> tcp: replace tcp_time_stamp_raw()
> tcp: rename tcp_skb_timestamp()
> tcp: move tcp_ns_to_ts() to net/ipv4/syncookies.c
> tcp: rename tcp_time_stamp() to tcp_time_stamp_ts()
> tcp: add tcp_rtt_tsopt_us()
> tcp: add RTAX_FEATURE_TCP_USEC_TS
> tcp: introduce TCP_PAWS_WRAP
> tcp: add support for usec resolution in TCP TS values
> tcp: add TCPI_OPT_USEC_TS
>
> .../chelsio/inline_crypto/chtls/chtls_cm.c | 2 +-
> include/linux/tcp.h | 9 ++-
> include/net/inet_timewait_sock.h | 3 +-
> include/net/tcp.h | 59 ++++++++++++++-----
> include/uapi/linux/rtnetlink.h | 18 +++---
> include/uapi/linux/tcp.h | 1 +
> net/ipv4/syncookies.c | 32 ++++++----
> net/ipv4/tcp.c | 26 +++++---
> net/ipv4/tcp_input.c | 52 ++++++++--------
> net/ipv4/tcp_ipv4.c | 5 +-
> net/ipv4/tcp_lp.c | 2 +-
> net/ipv4/tcp_minisocks.c | 19 ++++--
> net/ipv4/tcp_output.c | 14 +++--
> net/ipv4/tcp_timer.c | 44 +++++++++-----
> net/ipv6/tcp_ipv6.c | 5 +-
> net/netfilter/nf_synproxy_core.c | 2 +-
> .../selftests/bpf/progs/xdp_synproxy_kern.c | 4 +-
> 17 files changed, 193 insertions(+), 104 deletions(-)
>
> --
Thanks for sending this upstream, Eric! Great to have this upstream.
+1 to the nice benefits mentioned by Yuchung and Van.
The whole patch series looks great to me.
Acked-by: Neal Cardwell <ncardwell@...gle.com>
thanks,
neal
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