Date: Mon, 21 Jul 2025 07:59:49 GMT From: Michael Tuexen <tuexen@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: e0838f8a2e61 - main - tcp rack: fix sendmap app limited count tracking Message-ID: <202507210759.56L7xnQq061042@gitrepo.freebsd.org>
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The branch main has been updated by tuexen: URL: https://cgit.FreeBSD.org/src/commit/?id=e0838f8a2e61e73e37c1ae08eab9473daacaacb8 commit e0838f8a2e61e73e37c1ae08eab9473daacaacb8 Author: Peter Lei <peterlei@netflix.com> AuthorDate: 2025-07-21 07:56:03 +0000 Commit: Michael Tuexen <tuexen@FreeBSD.org> CommitDate: 2025-07-21 07:56:03 +0000 tcp rack: fix sendmap app limited count tracking rc_app_limited_cnt is an internal counter on the rack structure that tracks the number of sendmap entries that have the RACK_APP_LIMITED flag set. These entries gate goodput measurements. The counter is reported in a number of blackbox logging events. When a sendmap entry which has the RACK_APP_LIMITED flag set is cloned, the counter was not being maintained properly. While here, cleanup the counter check when a sendmap entry with the flag set is freed which previously hid this issue. Reviewed by: tuexen MFC after: 1 week Sponsored by: Netflix, Inc. --- sys/netinet/tcp_stacks/rack.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/sys/netinet/tcp_stacks/rack.c b/sys/netinet/tcp_stacks/rack.c index f52e6fbddfef..b0342b4e3165 100644 --- a/sys/netinet/tcp_stacks/rack.c +++ b/sys/netinet/tcp_stacks/rack.c @@ -3480,9 +3480,9 @@ static void rack_free(struct tcp_rack *rack, struct rack_sendmap *rsm) { if (rsm->r_flags & RACK_APP_LIMITED) { - if (rack->r_ctl.rc_app_limited_cnt > 0) { - rack->r_ctl.rc_app_limited_cnt--; - } + KASSERT((rack->r_ctl.rc_app_limited_cnt > 0), + ("app_cnt %u, rsm %p", rack->r_ctl.rc_app_limited_cnt, rsm)); + rack->r_ctl.rc_app_limited_cnt--; } if (rsm->r_limit_type) { /* currently there is only one limit type */ @@ -7044,6 +7044,9 @@ rack_clone_rsm(struct tcp_rack *rack, struct rack_sendmap *nrsm, /* Push bit must go to the right edge as well */ if (rsm->r_flags & RACK_HAD_PUSH) rsm->r_flags &= ~RACK_HAD_PUSH; + /* Update the count if app limited */ + if (nrsm->r_flags & RACK_APP_LIMITED) + rack->r_ctl.rc_app_limited_cnt++; /* Clone over the state of the hw_tls flag */ nrsm->r_hw_tls = rsm->r_hw_tls; /*
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