diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2025-06-17 16:19:04 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-06-17 16:19:05 -0700 |
| commit | 4b7da7341bea62d24fe2f06320f39368dec9603d (patch) | |
| tree | 14cc0ade0798fa4be0354a733325bb8e911b010d /net/ipv4/tcp.c | |
| parent | 90b4e1cf6de0793138b0f23ca5f9c52baad74bc9 (diff) | |
| parent | db16319efcc717a31dcb9c8f038acb6e4111c12e (diff) | |
Merge branch 'tcp-remove-obsolete-rfc3517-rfc6675-code'
Neal Cardwell says:
====================
tcp: remove obsolete RFC3517/RFC6675 code
RACK-TLP loss detection has been enabled as the default loss detection
algorithm for Linux TCP since 2018, in:
commit b38a51fec1c1 ("tcp: disable RFC6675 loss detection")
In case users ran into unexpected bugs or performance regressions,
that commit allowed Linux system administrators to revert to using
RFC3517/RFC6675 loss recovery by setting net.ipv4.tcp_recovery to 0.
In the seven years since 2018, our team has not heard reports of
anyone reverting Linux TCP to use RFC3517/RFC6675 loss recovery, and
we can't find any record in web searches of such a revert.
RACK-TLP was published as a standards-track RFC, RFC8985, in February
2021.
Several other major TCP implementations have default-enabled RACK-TLP
at this point as well.
RACK-TLP offers several significant performance advantages over
RFC3517/RFC6675 loss recovery, including much better performance in
the common cases of tail drops, lost retransmissions, and reordering.
It is now time to remove the obsolete and unused RFC3517/RFC6675 loss
recovery code. This will allow a substantial simplification of the
Linux TCP code base, and removes 12 bytes of state in every tcp_sock
for 64-bit machines (8 bytes on 32-bit machines).
To arrange the commits in reasonable sizes, this patch series is split
into 3 commits:
(1) Removes the core RFC3517/RFC6675 logic.
(2) Removes the RFC3517/RFC6675 hint state and the first layer of logic that
updates that state.
(3) Removes the emptied-out tcp_clear_retrans_hints_partial() helper function
and all of its call sites.
====================
Link: https://patch.msgid.link/20250615001435.2390793-1-ncardwell.sw@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/tcp.c')
| -rw-r--r-- | net/ipv4/tcp.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index f64f8276a73c..27d3ef83ce7b 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -5053,9 +5053,8 @@ static void __init tcp_struct_check(void) CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_tx, reordering); CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_tx, notsent_lowat); CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_tx, gso_segs); - CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_tx, lost_skb_hint); CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_tx, retransmit_skb_hint); - CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_read_tx, 40); + CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_read_tx, 32); /* TXRX read-mostly hotpath cache lines */ CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_txrx, tsoffset); |