Consider the currently in-use TCP options when
calculating the amount of new data to be injected during
SACK loss recovery. That addresses the effect that very small
(new) segments could be injected on partial ACKs while
still performing a SACK loss recovery.
Reported by: Liang Tian
Reviewed by: tuexen, chengc_netapp.com
MFC after: 2 weeks
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D26446
The fastpath in tcp_output tries to send out
full segments, and avoid sending partial segments by
comparing against the static t_maxseg variable.
That value does not consider tcp options like timestamps,
while the initial window calculation is using
the correct dynamic tcp_maxseg() function.
Due to this interaction, the last, full size segment
is considered too short and not sent out immediately.
Reviewed by: tuexen
MFC after: 2 weeks
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D26478
Remove most special treatment for ifnet TLS in the TCP stack, except
for code to avoid mixing handshakes and bulk data.
This code made heroic efforts to send down entire TLS records to
NICs. It was added to improve the PCIe bus efficiency of older TLS
offload NICs which did not keep state per-session, and so would need
to re-DMA the first part(s) of a TLS record if a TLS record was sent
in multiple TCP packets or TSOs. Newer TLS offload NICs do not need
this feature.
At Netflix, we've run extensive QoE tests which show that this feature
reduces client quality metrics, presumably because the effort to send
TLS records atomically causes the server to both wait too long to send
data (leading to buffers running dry), and to send too much data at
once (leading to packet loss).
Reviewed by: hselasky, jhb, rrs
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D26103
The use of t_rcvtime as proxy for the last transmission
fails for transactional IO, where the client requests
data before the server can respond with a bulk transfer.
Set aside a dedicated variable to actually track the last
locally sent segment going forward.
Reported by: rrs
Reviewed by: rrs, tuexen (mentor)
Approved by: tuexen (mentor), rgrimes (mentor)
MFC after: 2 weeks
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D25016
always want to do a window update, even when no data can be sent. Now in
cases where you are not pacing thats probably ok, you just send an extra
window update or two. However with bbr (and rack if its paced) every time
the pacer goes off its going to send a "window update".
Also in testing bbr I have found that if we are not responding to
data right away we end up staying in startup but incorrectly holding
a pacing gain of 192 (a loss). This is because the idle window code
does not restict itself to only work with PROBE_BW. In all other
states you dont want it doing a PROBE_BW state change.
Sponsored by: Netflix Inc.
Differential Revision: https://reviews.freebsd.org/D25247
Overly conservative data receivers may ignore the CWR flag
on other packets, and keep ECE latched. This can result in
continous reduction of the congestion window, and very poor
performance when ECN is enabled.
Reviewed by: rgrimes (mentor), rrs
Approved by: rgrimes (mentor), tuexen (mentor)
MFC after: 3 days
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D23364
While testing simultaneous open TCP with ECN, found that
negotiation fails to arrive at the expected final state.
Reviewed by: tuexen (mentor)
Approved by: tuexen (mentor), rgrimes (mentor)
MFC after: 2 weeks
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D23373
They have more differencies than similarities. For now there is lots
of code that would check for M_EXT only and work correctly on M_EXTPG
buffers, so still carry M_EXT bit together with M_EXTPG. However,
prepare some code for explicit check for M_EXTPG.
Reviewed by: gallatin
Differential Revision: https://reviews.freebsd.org/D24598
which can cause a TCP client to use invalid or stale TCP sequence numbers for ACK packets.
Packets with old sequence numbers are ignored and not used to update the send window size.
This might cause the TCP session to hang indefinitely under some circumstances.
Reported by: Cui Cheng
Reviewed by: tuexen (mentor), rgrimes (mentor)
Approved by: tuexen (mentor), rgrimes (mentor)
MFC after: 3 weeks
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D24515
This change is build on top of nexthop objects introduced in r359823.
Nexthops are separate datastructures, containing all necessary information
to perform packet forwarding such as gateway interface and mtu. Nexthops
are shared among the routes, providing more pre-computed cache-efficient
data while requiring less memory. Splitting the LPM code and the attached
data solves multiple long-standing problems in the routing layer,
drastically reduces the coupling with outher parts of the stack and allows
to transparently introduce faster lookup algorithms.
Route caching was (re)introduced to minimise (slow) routing lookups, allowing
for notably better performance for large TCP senders. Caching works by
acquiring rtentry reference, which is protected by per-rtentry mutex.
If the routing table is changed (checked by comparing the rtable generation id)
or link goes down, cache record gets withdrawn.
Nexthops have the same reference counting interface, backed by refcount(9).
This change merely replaces rtentry with the actual forwarding nextop as a
cached object, which is mostly mechanical. Other moving parts like cache
cleanup on rtable change remains the same.
Differential Revision: https://reviews.freebsd.org/D24340
While the original implementation of unmapped mbufs was a large
step forward in terms of reducing cache misses by enabling mbufs
to carry more than a single page for sendfile, they are rather
cache unfriendly when accessing the ext_pgs metadata and
data. This is because the ext_pgs part of the mbuf is allocated
separately, and almost guaranteed to be cold in cache.
This change takes advantage of the fact that unmapped mbufs
are never used at the same time as pkthdr mbufs. Given this
fact, we can overlap the ext_pgs metadata with the mbuf
pkthdr, and carry the ext_pgs meta directly in the mbuf itself.
Similarly, we can carry the ext_pgs data (TLS hdr/trailer/array
of pages) directly after the existing m_ext.
In order to be able to carry 5 pages (which is the minimum
required for a 16K TLS record which is not perfectly aligned) on
LP64, I've had to steal ext_arg2. The only user of this in the
xmit path is sendfile, and I've adjusted it to use arg1 when
using unmapped mbufs.
This change is almost entirely mechanical, except that we
change mb_alloc_ext_pgs() to no longer allow allocating
pkthdrs, the change to avoid ext_arg2 as mentioned above,
and the removal of the ext_pgs zone,
This change saves roughly 2% "raw" CPU (~59% -> 57%), or over
3% "scaled" CPU on a Netflix 100% software kTLS workload at
90+ Gb/s on Broadwell Xeons.
In a follow-on commit, I plan to remove some hacks to avoid
access ext_pgs fields of mbufs, since they will now be in
cache.
Many thanks to glebius for helping to make this better in
the Netflix tree.
Reviewed by: hselasky, jhb, rrs, glebius (early version)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D24213
For a Netflix 90Gb/s 100% TLS software kTLS workload, this reduces
the CPI of tcp_m_copym() from ~3.5 to ~2.5 as reported by vtune.
Reviewed by: jtl, rrs
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D23998
a single instance: use snd_recover also where sack_newdata was used.
Submitted by: Richard Scheffenegger
Differential Revision: https://reviews.freebsd.org/D18811
recovery. This is required by RFC 3168.
Submitted by: Richard Scheffenegger
Reviewed by: rgrimes@, tuexen@, Cheng Cui
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D23118
This makes it possible to retrieve per-connection statistical
information such as the receive window size, RTT, or goodput,
using a newly added TCP_STATS getsockopt(3) option, and extract
them using the stats_voistat_fetch(3) API.
See the net/tcprtt port for an example consumer of this API.
Compared to the existing TCP_INFO system, the main differences
are that this mechanism is easy to extend without breaking ABI,
and provides statistical information instead of raw "snapshots"
of values at a given point in time. stats(3) is more generic
and can be used in both userland and the kernel.
Reviewed by: thj
Tested by: thj
Obtained from: Netflix
Relnotes: yes
Sponsored by: Klara Inc, Netflix
Differential Revision: https://reviews.freebsd.org/D20655
This allows adding more ECN related flags in the future.
No functional change intended.
Submitted by: Richard Scheffenegger
Reviewed by: rrs@, tuexen@
Differential Revision: https://reviews.freebsd.org/D22497
including the TCP header in the first IP packet.
Enforce this in tcp_output(). In addition make sure that at least
one byte payload fits in the TCP segement to allow making progress.
Without this check, a kernel with INVARIANTS will panic.
This issue was found by running an instance of syzkaller.
Reviewed by: jtl@
MFC after: 3 days
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D21665
KTLS adds support for in-kernel framing and encryption of Transport
Layer Security (1.0-1.2) data on TCP sockets. KTLS only supports
offload of TLS for transmitted data. Key negotation must still be
performed in userland. Once completed, transmit session keys for a
connection are provided to the kernel via a new TCP_TXTLS_ENABLE
socket option. All subsequent data transmitted on the socket is
placed into TLS frames and encrypted using the supplied keys.
Any data written to a KTLS-enabled socket via write(2), aio_write(2),
or sendfile(2) is assumed to be application data and is encoded in TLS
frames with an application data type. Individual records can be sent
with a custom type (e.g. handshake messages) via sendmsg(2) with a new
control message (TLS_SET_RECORD_TYPE) specifying the record type.
At present, rekeying is not supported though the in-kernel framework
should support rekeying.
KTLS makes use of the recently added unmapped mbufs to store TLS
frames in the socket buffer. Each TLS frame is described by a single
ext_pgs mbuf. The ext_pgs structure contains the header of the TLS
record (and trailer for encrypted records) as well as references to
the associated TLS session.
KTLS supports two primary methods of encrypting TLS frames: software
TLS and ifnet TLS.
Software TLS marks mbufs holding socket data as not ready via
M_NOTREADY similar to sendfile(2) when TLS framing information is
added to an unmapped mbuf in ktls_frame(). ktls_enqueue() is then
called to schedule TLS frames for encryption. In the case of
sendfile_iodone() calls ktls_enqueue() instead of pru_ready() leaving
the mbufs marked M_NOTREADY until encryption is completed. For other
writes (vn_sendfile when pages are available, write(2), etc.), the
PRUS_NOTREADY is set when invoking pru_send() along with invoking
ktls_enqueue().
A pool of worker threads (the "KTLS" kernel process) encrypts TLS
frames queued via ktls_enqueue(). Each TLS frame is temporarily
mapped using the direct map and passed to a software encryption
backend to perform the actual encryption.
(Note: The use of PHYS_TO_DMAP could be replaced with sf_bufs if
someone wished to make this work on architectures without a direct
map.)
KTLS supports pluggable software encryption backends. Internally,
Netflix uses proprietary pure-software backends. This commit includes
a simple backend in a new ktls_ocf.ko module that uses the kernel's
OpenCrypto framework to provide AES-GCM encryption of TLS frames. As
a result, software TLS is now a bit of a misnomer as it can make use
of hardware crypto accelerators.
Once software encryption has finished, the TLS frame mbufs are marked
ready via pru_ready(). At this point, the encrypted data appears as
regular payload to the TCP stack stored in unmapped mbufs.
ifnet TLS permits a NIC to offload the TLS encryption and TCP
segmentation. In this mode, a new send tag type (IF_SND_TAG_TYPE_TLS)
is allocated on the interface a socket is routed over and associated
with a TLS session. TLS records for a TLS session using ifnet TLS are
not marked M_NOTREADY but are passed down the stack unencrypted. The
ip_output_send() and ip6_output_send() helper functions that apply
send tags to outbound IP packets verify that the send tag of the TLS
record matches the outbound interface. If so, the packet is tagged
with the TLS send tag and sent to the interface. The NIC device
driver must recognize packets with the TLS send tag and schedule them
for TLS encryption and TCP segmentation. If the the outbound
interface does not match the interface in the TLS send tag, the packet
is dropped. In addition, a task is scheduled to refresh the TLS send
tag for the TLS session. If a new TLS send tag cannot be allocated,
the connection is dropped. If a new TLS send tag is allocated,
however, subsequent packets will be tagged with the correct TLS send
tag. (This latter case has been tested by configuring both ports of a
Chelsio T6 in a lagg and failing over from one port to another. As
the connections migrated to the new port, new TLS send tags were
allocated for the new port and connections resumed without being
dropped.)
ifnet TLS can be enabled and disabled on supported network interfaces
via new '[-]txtls[46]' options to ifconfig(8). ifnet TLS is supported
across both vlan devices and lagg interfaces using failover, lacp with
flowid enabled, or lacp with flowid enabled.
Applications may request the current KTLS mode of a connection via a
new TCP_TXTLS_MODE socket option. They can also use this socket
option to toggle between software and ifnet TLS modes.
In addition, a testing tool is available in tools/tools/switch_tls.
This is modeled on tcpdrop and uses similar syntax. However, instead
of dropping connections, -s is used to force KTLS connections to
switch to software TLS and -i is used to switch to ifnet TLS.
Various sysctls and counters are available under the kern.ipc.tls
sysctl node. The kern.ipc.tls.enable node must be set to true to
enable KTLS (it is off by default). The use of unmapped mbufs must
also be enabled via kern.ipc.mb_use_ext_pgs to enable KTLS.
KTLS is enabled via the KERN_TLS kernel option.
This patch is the culmination of years of work by several folks
including Scott Long and Randall Stewart for the original design and
implementation; Drew Gallatin for several optimizations including the
use of ext_pgs mbufs, the M_NOTREADY mechanism for TLS records
awaiting software encryption, and pluggable software crypto backends;
and John Baldwin for modifications to support hardware TLS offload.
Reviewed by: gallatin, hselasky, rrs
Obtained from: Netflix
Sponsored by: Netflix, Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D21277
get BBRv1 into the tree. This fixes the DSACK bug but
is also needed by BBR. We have yet to go two more
one will be for the pacing code (tcp_ratelimit.c) and
the second will be for the new updated LRO code that
allows a transport to know the arrival times of packets
and (tcp_lro.c). After that we should finally be able
to get BBRv1 into head.
Sponsored by: Netflix Inc
Differential Revision: https://reviews.freebsd.org/D20908
was unlocked and yet the bucket-unlock flag was not
changed to false. This can cause a panic if INVARIANTS
is on and we go through the right path (though rare).
Reported by: syzbot+179a1ad49f3c4c215fa2@syzkaller.appspotmail.com
Reviewed by: tuexen@
MFC after: 1 week
When the TCP window scale option is not used, and the window
opens up enough in one soreceive, a window update will not be sent.
For example, if recwin == 65535, so->so_rcv.sb_hiwat >= 262144, and
so->so_rcv.sb_hiwat <= 524272, the window update will never be sent.
This is because recwin and adv are clamped to TCP_MAXWIN << tp->rcv_scale,
and so will never be >= so->so_rcv.sb_hiwat / 4
or <= so->so_rcv.sb_hiwat / 8.
This patch ensures a window update is sent if the window opens by
TCP_MAXWIN << tp->rcv_scale, which should only happen when the window
size goes from zero to the max expressible.
This issue looks like it was introduced in r306769 when recwin was clamped
to TCP_MAXWIN << tp->rcv_scale.
MFC after: 1 week
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D18821
zero. This was already done when sending them via tcp_respond().
Reviewed by: rrs@
MFC after: 1 week
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D17949
- Add a blank line before a block comment to match other block comments
in the same function.
- Sort the prototype for sbsndptr_adv and fix whitespace between return
type and function name.
Reviewed by: gallatin, bz
Differential Revision: https://reviews.freebsd.org/D17474
The following issues are fixed:
* Whenever a TCP server with TCP fast open enabled, calls accept(),
recv(), send(), and close() before the TCP-ACK segment has been received,
the TCP connection is just dropped and the reception of the TCP-ACK
segment triggers the sending of a TCP-RST segment.
* Whenever a TCP server with TCP fast open enabled, calls accept(), recv(),
send(), send(), and close() before the TCP-ACK segment has been received,
the first byte provided in the second send call is not transferred.
* Whenever a TCP client with TCP fast open enabled calls sendto() followed
by close() the TCP connection is just dropped.
Reviewed by: jtl@, kbowling@, rrs@
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D16485
time through the mbuf chain during copy and TSO limiting.
It is used by both Rack and now the FreeBSD stack.
Sponsored by: Netflix Inc
Differential Revision: https://reviews.freebsd.org/D15937
Rack includes the following features:
- A different SACK processing scheme (the old sack structures are not used).
- RACK (Recent acknowledgment) where counting dup-acks is no longer done
instead time is used to knwo when to retransmit. (see the I-D)
- TLP (Tail Loss Probe) where we will probe for tail-losses to attempt
to try not to take a retransmit time-out. (see the I-D)
- Burst mitigation using TCPHTPS
- PRR (partial rate reduction) see the RFC.
Once built into your kernel, you can select this stack by either
socket option with the name of the stack is "rack" or by setting
the global sysctl so the default is rack.
Note that any connection that does not support SACK will be kicked
back to the "default" base FreeBSD stack (currently known as "default").
To build this into your kernel you will need to enable in your
kernel:
makeoptions WITH_EXTRA_TCP_STACKS=1
options TCPHPTS
Sponsored by: Netflix Inc.
Differential Revision: https://reviews.freebsd.org/D15525
TCP's smoothed RTT (SRTT) can be much larger than an actual observed RTT. This can be either because of hz restricting the calculable RTT to 10ms in VMs or 1ms using the default 1000hz or simply because SRTT recently incorporated a larger value.
If an ACK arrives before the calculated badrxtwin (now + SRTT):
tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
We'll erroneously reset snd_una to snd_max. If multiple segments were dropped and this happens repeatedly the transmit rate will be limited to 1MSS per RTO until we've retransmitted all drops.
Reported by: rstone
Reviewed by: hiren, transport
Approved by: sbruno
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D8556
In r309610 and r315514 the behavior of handling EACCES was changed, and
tcp_output() now returns zero when EACCES happens. The reason of this
change was a hesitation that applications that use TCP-MD5 will be
affected by changes in project/ipsec.
TCP-MD5 code returns EACCES when security assocition for given connection
is not configured. But the same error code can return pfil(9), and this
change has affected connections blocked by pfil(9). E.g. application
doesn't return immediately when SYN segment is blocked, instead it waits
when several tries will be failed.
Actually, for TCP-MD5 application it doesn't matter will it get EACCES
after first SYN, or after several tries. Security associtions must be
configured before initiating TCP connection.
I left the EACCES in the switch() to show that it has special handling.
Reported by: Andreas Longwitz <longwitz at incore dot de>
MFC after: 10 days
summits at BSDCan and BSDCam in 2017.
The TCP Blackbox Recorder allows you to capture events on a TCP connection
in a ring buffer. It stores metadata with the event. It optionally stores
the TCP header associated with an event (if the event is associated with a
packet) and also optionally stores information on the sockets.
It supports setting a log ID on a TCP connection and using this to correlate
multiple connections that share a common log ID.
You can log connections in different modes. If you are doing a coordinated
test with a particular connection, you may tell the system to put it in
mode 4 (continuous dump). Or, if you just want to monitor for errors, you
can put it in mode 1 (ring buffer) and dump all the ring buffers associated
with the connection ID when we receive an error signal for that connection
ID. You can set a default mode that will be applied to a particular ratio
of incoming connections. You can also manually set a mode using a socket
option.
This commit includes only basic probes. rrs@ has added quite an abundance
of probes in his TCP development work. He plans to commit those soon.
There are user-space programs which we plan to commit as ports. These read
the data from the log device and output pcapng files, and then let you
analyze the data (and metadata) in the pcapng files.
Reviewed by: gnn (previous version)
Obtained from: Netflix, Inc.
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D11085
The conditional compilation support is now centralized in
tcp_fastopen.h and tcp_var.h. This doesn't provide the minimum
theoretical code/data footprint when TCP_RFC7413 is disabled, but
nearly all the TFO code should wind up being removed by the optimizer,
the additional footprint in the syncache entries is a single pointer,
and the additional overhead in the tcpcb is at the end of the
structure.
This enables the TCP_RFC7413 kernel option by default in amd64 and
arm64 GENERIC.
Reviewed by: hiren
MFC after: 1 month
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D14048
[RFC7413]. It also includes a pre-shared key mode of operation in
which the server requires the client to be in possession of a shared
secret in order to successfully open TFO connections with that server.
The names of some existing fastopen sysctls have changed (e.g.,
net.inet.tcp.fastopen.enabled -> net.inet.tcp.fastopen.server_enable).
Reviewed by: tuexen
MFC after: 1 month
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D14047
This reduces noise when kernel is compiled by newer GCC versions,
such as one used by external toolchain ports.
Reviewed by: kib, andrew(sys/arm and sys/arm64), emaste(partial), erj(partial)
Reviewed by: jhb (sys/dev/pci/* sys/kern/vfs_aio.c and sys/kern/kern_synch.c)
Differential Revision: https://reviews.freebsd.org/D10385
Mainly focus on files that use BSD 3-Clause license.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
can use them. Gather all TCP tunables in tcp_var.h in one place and
alphabetically sort them, to ease maintainance of the list.
Don't copy and paste declarations in tcp_stacks/fastpath.c.
