tcp: ensure tcp_sack_partialack does not inflate cwnd after RTO

The implicit assumption of snd_nxt always being larger than
snd_recover is not true after RTO. In that case, cwnd
would get inflated t

tcp: ensure tcp_sack_partialack does not inflate cwnd after RTO

The implicit assumption of snd_nxt always being larger than
snd_recover is not true after RTO. In that case, cwnd
would get inflated to ssthresh, which may be much larger
than the current pipe (data in flight).

Reviewed By: tuexen, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D43653

show more ...

tcp: commonize check for more data to send, style changes

Use SEQ_SUB instead of a plain subtraction, for an implict
type conversion and prevention of a possible overflow.
Use curly brackets in stac

tcp: commonize check for more data to send, style changes

Use SEQ_SUB instead of a plain subtraction, for an implict
type conversion and prevention of a possible overflow.
Use curly brackets in stacked if statements throughout.
Use of the ? operator to enhance readability when clearing
the FIN flag in tcp_output().

None of the above change the function.

Reviewed By: tuexen, cc, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D43539

show more ...

tcp: pass maxseg around instead of calculating locally

Improve slowpath processing (reordering, retransmissions)
slightly by calculating maxseg only once. This typically
saves one of two calls to tc

tcp: pass maxseg around instead of calculating locally

Improve slowpath processing (reordering, retransmissions)
slightly by calculating maxseg only once. This typically
saves one of two calls to tcp_maxseg().

Reviewed By: glebius, tuexen, cc, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D43536

show more ...

tcp: remove unused tcp_sack_output_debug() function

This debugging code has been lingering for years with
no known use.

No functional change.

Reviewed by: tuexen, #transport
Sponsored by

tcp: remove unused tcp_sack_output_debug() function

This debugging code has been lingering for years with
no known use.

No functional change.

Reviewed by: tuexen, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D43511

show more ...

tcp: do not purge SACK scoreboard on first RTO

Keeping the SACK scoreboard intact after the first RTO
and retransmitting all data anew only on subsequent RTOs
allows a more timely and efficient loss

tcp: do not purge SACK scoreboard on first RTO

Keeping the SACK scoreboard intact after the first RTO
and retransmitting all data anew only on subsequent RTOs
allows a more timely and efficient loss recovery under
many adverse cirumstances.

Reviewed By: tuexen, #transport
MFC after: 10 weeks
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D42906

show more ...

tcp: for LRD move sysctl from tcp.do_lrd tp tcp.sack.lrd, remove sockopt

Moving lrd sysctl to the tcp.sack branch, since LRD only works with SACK.
Remove the sockopt to programmatically control LRD

tcp: for LRD move sysctl from tcp.do_lrd tp tcp.sack.lrd, remove sockopt

Moving lrd sysctl to the tcp.sack branch, since LRD only works with SACK.
Remove the sockopt to programmatically control LRD per session.

Reviewed By: #transport, tuexen, rrs
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D42851

show more ...

sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl s

sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

show more ...

[tcp] add PRR 6937bis heuristic and retire prr_conservative sysctl

Improve Proportional Rate Reduction (RFC6937) by using a
heuristic, which automatically chooses between
conservative CRB and more a

[tcp] add PRR 6937bis heuristic and retire prr_conservative sysctl

Improve Proportional Rate Reduction (RFC6937) by using a
heuristic, which automatically chooses between
conservative CRB and more aggressive SSRB modes.
Only when snd_una advances (a partial ACK), SSRB may be
used. Also, that ACK must not have any indication of
ongoing loss - using the addition of new holes into the
scoreboard as proxy for such an event.

MFC after: 4 weeks
Reviewed By: #transport, kbowling, rrs
Sponsored By: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D28822

show more ...

tcp: use signed IsLost() related accounting variables

Coverity found that one safety check (kassert) was not
functional, as possible incorrect subtractions during
the accounting wouldn't show up as

tcp: use signed IsLost() related accounting variables

Coverity found that one safety check (kassert) was not
functional, as possible incorrect subtractions during
the accounting wouldn't show up as (invalid) negative
values.

Reported by: gallatin
Reviewed By: cc, #transport
Sponsored By: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D42180

show more ...

tcp: clear SACK state when scoreboard is forcefully freed

When a Retransmission Timeout happens during an on-going SACK loss recovery
episode, the internal SACK accounting was not cleared.

Reported

tcp: clear SACK state when scoreboard is forcefully freed

When a Retransmission Timeout happens during an on-going SACK loss recovery
episode, the internal SACK accounting was not cleared.

Reported by: pho
Reviewed By: tuexen, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D42162

show more ...

tcp: include RFC6675 IsLost() in pipe calculation

Add more accounting while processing SACK data, to
keep track of when a packet is deemed lost using
the RFC6675 guidance.

Together with PRR (RFC697

tcp: include RFC6675 IsLost() in pipe calculation

Add more accounting while processing SACK data, to
keep track of when a packet is deemed lost using
the RFC6675 guidance.

Together with PRR (RFC6972) this allows a sender to
retransmit presumed lost packets faster, and loss
recovery to complete earlier.

Reviewed By: cc, rrs, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D39299

show more ...

sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

tcp: send SACK rescue retransmission also mid-stream

Previously, SACK rescue retransmissions would only happen
on a loss recovery at the tail end of the send buffer.

This extends the mechanism such

tcp: send SACK rescue retransmission also mid-stream

Previously, SACK rescue retransmissions would only happen
on a loss recovery at the tail end of the send buffer.

This extends the mechanism such that partial ACKs without SACK
mid-stream also trigger a rescue retransmission to try avoid
an otherwise unavoidable retransmission timeout.

Reviewed By: tuexen, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D39274

show more ...

tcp: retire TCPDEBUG

This subsystem is superseded by modern debugging facilities,
e.g. DTrace probes and TCP black box logging.

We intentionally leave SO_DEBUG in place, as many utilities may
set i

tcp: retire TCPDEBUG

This subsystem is superseded by modern debugging facilities,
e.g. DTrace probes and TCP black box logging.

We intentionally leave SO_DEBUG in place, as many utilities may
set it on a socket. Also the tcp::debug DTrace probes look at
this flag on a socket.

Reviewed by: gnn, tuexen
Discussed with: rscheff, rrs, jtl
Differential revision: https://reviews.freebsd.org/D37694

show more ...

tcp: provide macros to access inpcb and socket from a tcpcb

There should be no functional changes with this commit.

Reviewed by: rscheff
Differential revision: https://reviews.freebsd.org/D37123

tcp: remove unnecessary include of tcp6_var.h

Reviewed by: rscheff, melifaro
Differential revision: https://reviews.freebsd.org/D36725

tcp: exclude KASSERTS when rescue retransmissions are in play.

The KASSERT criteria needs to be checked against the
sendbuffer so_snd in a subsequent version.

Reviewed By: tuexen, #transport
PR: 2

tcp: exclude KASSERTS when rescue retransmissions are in play.

The KASSERT criteria needs to be checked against the
sendbuffer so_snd in a subsequent version.

Reviewed By: tuexen, #transport
PR: 263445
MFC after: 1 week
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D35431

show more ...

tcp: remove goto and address another NULL deref in SACK

Missed another NULL dereference during KASSERTS after traversing
the scoreboard. While at it, scratch the goto by making the
traversal conditi

tcp: remove goto and address another NULL deref in SACK

Missed another NULL dereference during KASSERTS after traversing
the scoreboard. While at it, scratch the goto by making the
traversal conditional, and remove duplicate checks using an
unconditional loop with all checks inside.

Reviewed By: hselasky
PR: 263445
MFC after: 1 week
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D35428

show more ...

tcp: skip sackhole checks on NULL

Inadvertedly introduced NULL pointer dereference during
sackhole sanity check in D35387.

Reviewed By: glebius
PR: 263445
MFC after: 1 week
Sponsored by: NetApp, I

tcp: skip sackhole checks on NULL

Inadvertedly introduced NULL pointer dereference during
sackhole sanity check in D35387.

Reviewed By: glebius
PR: 263445
MFC after: 1 week
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D35423

show more ...

tcp: Sanity check of SACK holes on retransmissions

Adding a few KASSERT() to validate sanity of sack holes, and
bail out if sack hole is inconsistent to avoid panicing non-invariant builds.

Reviewe

tcp: Sanity check of SACK holes on retransmissions

Adding a few KASSERT() to validate sanity of sack holes, and
bail out if sack hole is inconsistent to avoid panicing non-invariant builds.

Reviewed By: hselasky, glebius
PR: 263445
MFC after: 1 week
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D35387

show more ...

tcp: Warning cleanup from new compiler.

The clang compiler recently got an update that generates warnings of unused
variables where they were set, and then never used. This revision goes through
the

tcp: Warning cleanup from new compiler.

The clang compiler recently got an update that generates warnings of unused
variables where they were set, and then never used. This revision goes through
the tcp stack and cleans all of those up.

Reviewed by: Michael Tuexen, Gleb Smirnoff
Sponsored by: Netflix Inc.
Differential Revision:

show more ...

tcp: mechanically substitute call to tfb_tcp_output to new method.

Made with sed(1) execution:

sed -Ef sed -i "" $(grep --exclude tcp_var.h -lr tcp_output sys/)

sed:
s/tp->t_fb->tfb_tcp_output\(tp

tcp: mechanically substitute call to tfb_tcp_output to new method.

Made with sed(1) execution:

sed -Ef sed -i "" $(grep --exclude tcp_var.h -lr tcp_output sys/)

sed:
s/tp->t_fb->tfb_tcp_output\(tp\)/tcp_output(tp)/
s/to tfb_tcp_output\(\)/to tcp_output()/

Reviewed by: rrs, tuexen
Differential revision: https://reviews.freebsd.org/D33366

show more ...

tcp: Make dsack stats available in netstat and also make sure its aware of TLP's.

DSACK accounting has been for quite some time under a NETFLIX_STATS ifdef. Statistics
on DSACKs however are very use

tcp: Make dsack stats available in netstat and also make sure its aware of TLP's.

DSACK accounting has been for quite some time under a NETFLIX_STATS ifdef. Statistics
on DSACKs however are very useful in figuring out how much bad retransmissions you
are doing. This is further complicated, however, by stacks that do TLP. A TLP
when discovering a lost ack in the reverse path will cause the generation
of a DSACK. For this situation we introduce a new dsack-tlp-bytes as well
as the more traditional dsack-bytes and dsack-packets. These will now
all display in netstat -p tcp -s. This also updates all stacks that
are currently built to keep track of these stats.

Reviewed by: tuexen
Sponsored by: Netflix Inc.
Differential Revision: https://reviews.freebsd.org/D32158

show more ...

tcp: SACK Lost Retransmission Detection (LRD)

Recover from excessive losses without reverting to a
retransmission timeout (RTO). Disabled by default, enable
with sysctl net.inet.tcp.do_lrd=1

Review

tcp: SACK Lost Retransmission Detection (LRD)

Recover from excessive losses without reverting to a
retransmission timeout (RTO). Disabled by default, enable
with sysctl net.inet.tcp.do_lrd=1

Reviewed By: #transport, rrs, tuexen, #manpages
Sponsored by: Netapp, Inc.
Differential Revision: https://reviews.freebsd.org/D28931

show more ...

This brings into sync FreeBSD with the netflix versions of rack and bbr.
This fixes several breakages (panics) since the tcp_lro code was
committed that have been reported. Quite a few new features a

This brings into sync FreeBSD with the netflix versions of rack and bbr.
This fixes several breakages (panics) since the tcp_lro code was
committed that have been reported. Quite a few new features are
now in rack (prefecting of DGP -- Dynamic Goodput Pacing among the
largest). There is also support for ack-war prevention. Documents
comming soon on rack..

Sponsored by: Netflix
Reviewed by: rscheff, mtuexen
Differential Revision: https://reviews.freebsd.org/D30036

show more ...