From: Jakub Kicinski Date: Tue, 17 Jun 2025 23:19:04 +0000 (-0700) Subject: Merge branch 'tcp-remove-obsolete-rfc3517-rfc6675-code' X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4b7da7341bea62d24fe2f06320f39368dec9603d;p=thirdparty%2Flinux.git 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 --- 4b7da7341bea62d24fe2f06320f39368dec9603d