from xnu sources. If we encounter a network where ICMP is blocked
the Needs Frag indicator may not propagate back to us. Attempt to
downshift the mss once to a preconfigured value.
Default this feature to off for now while we do not have a full PLPMTUD
implementation in our stack.
Adds the following new sysctl's for control:
net.inet.tcp.pmtud_blackhole_detection -- turns on/off this feature
net.inet.tcp.pmtud_blackhole_mss -- mss to try for ipv4
net.inet.tcp.v6pmtud_blackhole_mss -- mss to try for ipv6
Adds the following new sysctl's for monitoring:
-- Number of times the code was activated to attempt a mss downshift
net.inet.tcp.pmtud_blackhole_activated
-- Number of times the blackhole mss was used in an attempt to downshift
net.inet.tcp.pmtud_blackhole_min_activated
-- Number of times that we failed to connect after we downshifted the mss
net.inet.tcp.pmtud_blackhole_failed
Phabricator: https://reviews.freebsd.org/D506
Reviewed by: rpaulo bz
MFC after: 2 weeks
Relnotes: yes
Sponsored by: Limelight Networks
- tcp_get_sav() - SADB key lookup
- tcp_signature_do_compute() - actual computation
* Fix TCP signature case for listening socket:
do not assume EVERY connection coming to socket
with TCP_SIGNATURE set to be md5 signed regardless
of SADB key existance for particular address. This
fixes the case for routing software having _some_
BGP sessions secured by md5.
* Simplify TCP_SIGNATURE handling in tcp_input()
MFC after: 2 weeks
The current TSO limitation feature only takes the total number of
bytes in an mbuf chain into account and does not limit by the number
of mbufs in a chain. Some kinds of hardware is limited by two
factors. One is the fragment length and the second is the fragment
count. Both of these limits need to be taken into account when doing
TSO. Else some kinds of hardware might have to drop completely valid
mbuf chains because they cannot loaded into the given hardware's DMA
engine. The new way of doing TSO limitation has been made backwards
compatible as input from other FreeBSD developers and will use
defaults for values not set.
Reviewed by: adrian, rmacklem
Sponsored by: Mellanox Technologies
MFC after: 1 week
eight years. The original concept was to improve the
corner case where you run out of ephemeral ports, but it
was causing performance problems and the mechanism
of limiting the number of time_wait sockets serves
the same purpose in the end.
Reviewed by: bz
same events that tcpstat's tcps_rcvmemdrop counter counts.
- Rename tcps_rcvmemdrop to tcps_rcvreassfull and improve its
description in netstat(1) output.
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
mixing on stack memory and UMA memory in one linked list.
Thus, rewrite TCP reassembly code in terms of memory usage. The
algorithm remains unchanged.
We actually do not need extra memory to build a reassembly queue.
Arriving mbufs are always packet header mbufs. So we got the length
of data as pkthdr.len. We got m_nextpkt for linkage. And we need
only one pointer to point at the tcphdr, use PH_loc for that.
In tcpcb the t_segq fields becomes mbuf pointer. The t_segqlen
field now counts not packets, but bytes in the queue. This gives
us more precision when comparing to socket buffer limits.
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
walks the list of connections in TIME_WAIT closing expired connections
due to contention on the global TCP pcbinfo lock.
To remediate, introduce a new global lock to protect the list of
connections in TIME_WAIT. Only acquire the TCP pcbinfo lock when
closing an expired connection. This limits the window of time when
TCP input processing is stopped to the amount of time needed to close
a single connection.
Submitted by: Julien Charbon <jcharbon@verisign.com>
Reviewed by: rwatson, rrs, adrian
MFC after: 2 months
were primarily used to size the sysctl name list macros that were removed
in r254295. A few other constants either did not have an associated
sysctl node, or the associated node used OID_AUTO instead.
PR: ports/184525 (exp-run)
so that fixed TCP_SIGNATURE handling can later be merged.
This is derived from follow-up work to SVN r183001 posted to
net@ on Sep 13 2008.
Approved by: re (gjb)
dynamic translation so that their arguments match the definitions for
these providers in Solaris and illumos. Thus, existing scripts for these
providers should work unmodified on FreeBSD.
Tested by: gnn, hiren
MFC after: 1 month
limited in the amount of data they can handle at once.
Drivers can set ifp->if_hw_tsomax before calling ether_ifattach() to
change the limit.
The lowest allowable size is IP_MAXPACKET / 8 (8192 bytes) as anything
less wouldn't be very useful anymore. The upper limit is still at
IP_MAXPACKET (65536 bytes). Raising it requires further auditing of
the IPv4/v6 code path's as the length field in the IP header would
overflow leading to confusion in firewalls and others packet handler on
the real size of the packet.
The placement into "struct ifnet" is a bit hackish but the best place
that was found. When the stack/driver boundary is updated it should
be handled in a better way.
Submitted by: cperciva (earlier version)
Reviewed by: cperciva
Tested by: cperciva
MFC after: 1 week (using spare struct members to preserve ABI)
Convert 'struct ipstat' and 'struct tcpstat' to counter(9).
This speeds up IP forwarding at extreme packet rates, and
makes accounting more precise.
Sponsored by: Nginx, Inc.
draft-ietf-tcpm-initcwnd-05. It explains why the increased initial
window improves the overall performance of many web services without
risking congestion collapse.
As long as it remains a draft it is placed under a sysctl marking it
as experimental:
net.inet.tcp.experimental.initcwnd10 = 1
When it becomes an official RFC soon the sysctl will be changed to
the RFC number and moved to net.inet.tcp.
This implementation differs from the RFC draft in that it is a bit
more conservative in the case of packet loss on SYN or SYN|ACK because
we haven't reduced the default RTO to 1 second yet. Also the restart
window isn't yet increased as allowed. Both will be adjusted with
upcoming changes.
Is is enabled by default. In Linux it is enabled since kernel 3.0.
MFC after: 2 weeks
- Stateful TCP offload drivers for Terminator 3 and 4 (T3 and T4) ASICs.
These are available as t3_tom and t4_tom modules that augment cxgb(4)
and cxgbe(4) respectively. The cxgb/cxgbe drivers continue to work as
usual with or without these extra features.
- iWARP driver for Terminator 3 ASIC (kernel verbs). T4 iWARP in the
works and will follow soon.
Build-tested with make universe.
30s overview
============
What interfaces support TCP offload? Look for TOE4 and/or TOE6 in the
capabilities of an interface:
# ifconfig -m | grep TOE
Enable/disable TCP offload on an interface (just like any other ifnet
capability):
# ifconfig cxgbe0 toe
# ifconfig cxgbe0 -toe
Which connections are offloaded? Look for toe4 and/or toe6 in the
output of netstat and sockstat:
# netstat -np tcp | grep toe
# sockstat -46c | grep toe
Reviewed by: bz, gnn
Sponsored by: Chelsio communications.
MFC after: ~3 months (after 9.1, and after ensuring MFC is feasible)
proposed MTU value from it and update the TCP host cache. Then
tcp_mss_update() is called on the corresponding tcpcb. It finds the
just allocated entry in the TCP host cache and updates MSS on the
tcpcb. And then we do a fast retransmit of what we have in the tcp
send buffer.
This sequence gets broken if the TCP host cache is exausted. In this
case allocation fails, and later called tcp_mss_update() finds nothing
in cache. The fast retransmit is done with not reduced MSS and is
immidiately replied by remote host with new ICMP datagrams and the
cycle repeats. This ping-pong can go up to wirespeed.
To fix this:
- tcp_mss_update() gets new parameter - mtuoffer, that is like
offer, but needs to have min_protoh subtracted.
- tcp_mtudisc() as notification method renamed to tcp_mtudisc_notify().
- tcp_mtudisc() now accepts not a useless error argument, but proposed
MTU value, that is passed to tcp_mss_update() as mtuoffer.
Reported by: az
Reported by: Andrey Zonov <andrey zonov.org>
Reviewed by: andre (previous version of patch)
TCP_KEEPCNT, that allow to control initial timeout, idle time, idle
re-send interval and idle send count on a per-socket basis.
Reviewed by: andre, bz, lstewart
long been superseded by the RFC3390 initial CWND sizing.
Also remove the remnants of TCP_METRICS_CWND which used the
TCP hostcache to set the initial CWND in a non-RFC compliant
way.
MFC after: 1 week
- TCP keep* timers
- TCP UTO (adjust from what was there already)
- netmap
- route caching
- user cookie (temporary to allow for the real fix)
Slightly re-shuffle struct ifnet moving fields out of the middle
of spares and to better align.
Discussed with: rwatson (slightly earlier version)
persist state and the retransmit timer. However, the code that implements
"bad retransmit recovery" only checks t_rxtshift to see if an ACK has been
received in during the first retransmit timeout window. As a result, if
ticks has wrapped over to a negative value and a socket is in the persist
state, it can incorrectly treat an ACK from the remote peer as a
"bad retransmit recovery" and restore saved values such as snd_ssthresh and
snd_cwnd. However, if the socket has never had a retransmit timeout, then
these saved values will be zero, so snd_ssthresh and snd_cwnd will be set
to 0.
If the socket is in fast recovery (this can be caused by excessive
duplicate ACKs such as those fixed by 220794), then each ACK that arrives
triggers either NewReno or SACK partial ACK handling which clamps snd_cwnd
to be no larger than snd_ssthresh. In effect, the socket's send window
is permamently stuck at 0 even though the remote peer is advertising a
much larger window and pending data is only sent via TCP window probes
(so one byte every few seconds).
Fix this by adding a new TCP pcb flag (TF_PREVVALID) that indicates that
the various snd_*_prev fields in the pcb are valid and only perform
"bad retransmit recovery" if this flag is set in the pcb. The flag is set
on the first retransmit timeout that occurs and is cleared on subsequent
retransmit timeouts or when entering the persist state.
Reviewed by: bz
MFC after: 2 weeks
As long as this is a costy function, even when compiled in (along with
the option TCP_SIGNATURE), it can be disabled via the
net.inet.tcp.signature_verify_input sysctl.
Sponsored by: Sandvine Incorporated
Reviewed by: emaste, bz
MFC after: 2 weeks
access inbound/outbound events and associated data for established TCP
connections. The hooks only run if at least one hook function is registered
for the hook point, ensuring the impact on the stack is effectively nil when
no TCP Khelp modules are loaded. struct tcp_hhook_data is passed as contextual
data to any registered Khelp module hook functions.
- Add an OSD (Object Specific Data) pointer to struct tcpcb to allow Khelp
modules to associate per-connection data with the TCP control block.
- Bump __FreeBSD_version and add a note to UPDATING regarding to ABI changes
introduced by this commit and r216753.
In collaboration with: David Hayes <dahayes at swin edu au> and
Grenville Armitage <garmitage at swin edu au>
Sponsored by: FreeBSD Foundation
Reviewed by: bz, others along the way
MFC after: 3 months
This will be used by the incoming Enhanced RTT Khelp module.
Sponsored by: FreeBSD Foundation
Submitted by: David Hayes <dahayes at swin edu au>
Reviewed by: bz and others (as part of a larger patch)
MFC after: 3 months
Retransmitted Packets
Zero Window Advertisements
Out of Order Receives
These statistics are available via the -T argument to
netstat(1).
MFC after: 2 weeks
Control Algorithms for FreeBSD" FreeBSD Foundation funded project. More details
about the project are available at: http://caia.swin.edu.au/freebsd/5cc/
- Add a KPI and supporting infrastructure to allow modular congestion control
algorithms to be used in the net stack. Algorithms can maintain per-connection
state if required, and connections maintain their own algorithm pointer, which
allows different connections to concurrently use different algorithms. The
TCP_CONGESTION socket option can be used with getsockopt()/setsockopt() to
programmatically query or change the congestion control algorithm respectively
from within an application at runtime.
- Integrate the framework with the TCP stack in as least intrusive a manner as
possible. Care was also taken to develop the framework in a way that should
allow integration with other congestion aware transport protocols (e.g. SCTP)
in the future. The hope is that we will one day be able to share a single set
of congestion control algorithm modules between all congestion aware transport
protocols.
- Introduce a new congestion recovery (TF_CONGRECOVERY) state into the TCP stack
and use it to decouple the meaning of recovery from a congestion event and
recovery from packet loss (TF_FASTRECOVERY) a la RFC2581. ECN and delay based
congestion control protocols don't generally need to recover from packet loss
and need a different way to note a congestion recovery episode within the
stack.
- Remove the net.inet.tcp.newreno sysctl, which simplifies some portions of code
and ensures the stack always uses the appropriate mechanisms for recovering
from packet loss during a congestion recovery episode.
- Extract the NewReno congestion control algorithm from the TCP stack and
massage it into module form. NewReno is always built into the kernel and will
remain the default algorithm for the forseeable future. Implementations of
additional different algorithms will become available in the near future.
- Bump __FreeBSD_version to 900025 and note in UPDATING that rebuilding code
that relies on the size of "struct tcpcb" is required.
Many thanks go to the Cisco University Research Program Fund at Community
Foundation Silicon Valley and the FreeBSD Foundation. Their support of our work
at the Centre for Advanced Internet Architectures, Swinburne University of
Technology is greatly appreciated.
In collaboration with: David Hayes <dahayes at swin edu au> and
Grenville Armitage <garmitage at swin edu au>
Sponsored by: Cisco URP, FreeBSD Foundation
Reviewed by: rpaulo
Tested by: David Hayes (and many others over the years)
MFC after: 3 months
not be used outside of the reassembly queue implementation. Provide a new
function to flush all segments from a reassembly queue and call it from the
appropriate places instead of manipulating the queue directly.
Sponsored by: FreeBSD Foundation
Reviewed by: andre, gnn, rpaulo
MFC after: 2 weeks
to give way for the pluggable congestion control framework. It is
the task of the congestion control algorithm to set the congestion
window and amount of inflight data without external interference.
In 'struct tcpcb' the variables previously used by the inflight
limiter are renamed to spares to keep the ABI intact and to have
some more space for future extensions.
In 'struct tcp_info' the variable 'tcpi_snd_bwnd' is not removed to
preserve the ABI. It is always set to 0.
In siftr.c in 'struct pkt_node' the variable 'snd_bwnd' is not removed
to preserve the ABI. It is always set to 0.
These unused variable in the various structures may be reused in the
future or garbage collected before the next release or at some other
point when an ABI change happens anyway for other reasons.
No MFC is planned. The inflight bandwidth limiter stays disabled by
default in the other branches but remains available.
it must reset its congestion window back to the initial window.
RFC3390 has increased the initial window from 1 segment to up to
4 segments.
The initial window increase of RFC3390 wasn't reflected into the
restart window which remained at its original defaults of 4 segments
for local and 1 segment for all other connections. Both values are
controllable through sysctl net.inet.tcp.local_slowstart_flightsize
and net.inet.tcp.slowstart_flightsize.
The increase helps TCP's slow start algorithm to open up the congestion
window much faster.
Reviewed by: lstewart
MFC after: 1 week
sysctl's and remove any side effects.
Both sysctl's share the same backend infrastructure and due to the
way it was implemented enabling net.inet.tcp.log_in_vain would also
cause log_debug output to be generated. This was surprising and
eventually annoying to the user.
The log output backend is kept the same but a little shim is inserted
to properly separate log_in_vain and log_debug and to remove any side
effects.
PR: kern/137317
MFC after: 1 week
"Whitspace" churn after the VIMAGE/VNET whirls.
Remove the need for some "init" functions within the network
stack, like pim6_init(), icmp_init() or significantly shorten
others like ip6_init() and nd6_init(), using static initialization
again where possible and formerly missed.
Move (most) variables back to the place they used to be before the
container structs and VIMAGE_GLOABLS (before r185088) and try to
reduce the diff to stable/7 and earlier as good as possible,
to help out-of-tree consumers to update from 6.x or 7.x to 8 or 9.
This also removes some header file pollution for putatively
static global variables.
Revert VIMAGE specific changes in ipfilter::ip_auth.c, that are
no longer needed.
Reviewed by: jhb
Discussed with: rwatson
Sponsored by: The FreeBSD Foundation
Sponsored by: CK Software GmbH
MFC after: 6 days
to not leak them, otherwise making UMA/vmstat unhappy with every stoped vnet.
We will still leak pages (especially for zones marked NOFREE).
Reshuffle cleanup order in tcp_destroy() to get rid of what we can
easily free first.
Sponsored by: ISPsystem
Reviewed by: rwatson
MFC after: 5 days
feature when you have a seemingly stuck socket and want to figure
out why it has not been closed yet.
No plans to MFC this, as it changes the netstat sysctl ABI.
Reviewed by: andre, rwatson, Eric Van Gyzen
all pertinent statatistics for the subsystem. These structures are
sometimes "borrowed" by kernel modules that require a place to store
statistics for similar events.
Add KPI accessor functions for statistics structures referenced by kernel
modules so that they no longer encode certain specifics of how the data
structures are named and stored. This change is intended to make it
easier to move to per-CPU network stats following 8.0-RELEASE.
The following modules are affected by this change:
if_bridge
if_cxgb
if_gif
ip_mroute
ipdivert
pf
In practice, most of these statistics consumers should, in fact, maintain
their own statistics data structures rather than borrowing structures
from the base network stack. However, that change is too agressive for
this point in the release cycle.
Reviewed by: bz
Approved by: re (kib)
(DPCPU), as suggested by Peter Wemm, and implement a new per-virtual
network stack memory allocator. Modify vnet to use the allocator
instead of monolithic global container structures (vinet, ...). This
change solves many binary compatibility problems associated with
VIMAGE, and restores ELF symbols for virtualized global variables.
Each virtualized global variable exists as a "reference copy", and also
once per virtual network stack. Virtualized global variables are
tagged at compile-time, placing the in a special linker set, which is
loaded into a contiguous region of kernel memory. Virtualized global
variables in the base kernel are linked as normal, but those in modules
are copied and relocated to a reserved portion of the kernel's vnet
region with the help of a the kernel linker.
Virtualized global variables exist in per-vnet memory set up when the
network stack instance is created, and are initialized statically from
the reference copy. Run-time access occurs via an accessor macro, which
converts from the current vnet and requested symbol to a per-vnet
address. When "options VIMAGE" is not compiled into the kernel, normal
global ELF symbols will be used instead and indirection is avoided.
This change restores static initialization for network stack global
variables, restores support for non-global symbols and types, eliminates
the need for many subsystem constructors, eliminates large per-subsystem
structures that caused many binary compatibility issues both for
monitoring applications (netstat) and kernel modules, removes the
per-function INIT_VNET_*() macros throughout the stack, eliminates the
need for vnet_symmap ksym(2) munging, and eliminates duplicate
definitions of virtualized globals under VIMAGE_GLOBALS.
Bump __FreeBSD_version and update UPDATING.
Portions submitted by: bz
Reviewed by: bz, zec
Discussed with: gnn, jamie, jeff, jhb, julian, sam
Suggested by: peter
Approved by: re (kensmith)
the TCP syncache. This returns struct tcpopt to being private within the TCP
implementation, thus allowing it to be modified without ABI concerns.
The patch breaks the ABI. Bump __FreeBSD_version to 800103 accordingly. The cxgb
driver is the only TOE consumer affected by this change, and needs to be
recompiled along with the kernel.
Suggested by: rwatson
Reviewed by: rwatson, kmacy
Approved by: re (kensmith), kensmith (mentor temporarily unavailable)
