to the higher of the previous ssthresh or 3/4 of the prior cwnd.
Submitted by: Richard Scheffenegger
Reviewed by: Cheng Cui
Differential Revision: https://reviews.freebsd.org/D18982
This is descrined in RFC 6582, which updates RFC 3782.
Submitted by: Richard Scheffenegger
Reviewed by: lstewart@
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D17614
This change is causing TCP connections using cubic to hang. Need to dig more to
find exact cause and fix it.
Reported by: tj at mrsk dot me, Matt Garber (via twitter)
Discussed with: sbruno (previously), allanjude, cperciva
MFC after: 3 days
When ABE was added (rS331214) to NewReno and leak fixed (rS333699) , it now has
a destructor (newreno_cb_destroy) for per connection state. Other congestion
controls may allocate and free cc_data on entry and exit, but the field is
never explicitly NULLed if moving back to NewReno which only internally
allocates stateful data (no entry contstructor) resulting in a situation where
newreno_cb_destory might be called on a junk pointer.
- NULL out cc_data in the framework after calling {cc}_cb_destroy
- free(9) checks for NULL so there is no need to perform not NULL checks
before calling free.
- Improve a comment about NewReno in tcp_ccalgounload
This is the result of a debugging session from Jason Wolfe, Jason Eggleston,
and mmacy@ and very helpful insight from lstewart@.
Submitted by: Kevin Bowling
Reviewed by: lstewart
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D16282
Singed calculations in cubic_cwnd() can result in negative cwnd
value which is then cast to an unsigned value. Values less than
1 mss are generally bad for other parts of the code, also fixed.
Submitted by: Jason Eggleston <jason@eggnet.com>
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D14141
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
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.
No functional change intended.
r307901 was reverted in r321480, restoring an incorrect block
delimitation bug present in the original cc_cubic commit. Restore
only the bugfix (brace addition) from r307901.
CID: 1090182
Approved by: sbruno
This was discussed between various transport@ members and it was
requested to be reverted and discussed.
Submitted by: Kevin Bowling <kevin.bowling@kev009.com>
Reported by: lawrence
Reviewed by: hiren
Sponsored by: Limelight Networks
loss event but not use or obay the recommendations i.e. values set by it in some
cases.
Here is an attempt to solve that confusion by following relevant RFCs/drafts.
Stack only sets congestion window/slow start threshold values when there is no
CC module availalbe to take that action. All CC modules are inspected and
updated when needed to take appropriate action on loss.
tcp_stacks/fastpath module has been updated to adapt these changes.
Note: Probably, the most significant change would be to not bring congestion
window down to 1MSS on a loss signaled by 3-duplicate acks and letting
respective CC decide that value.
In collaboration with: Matt Macy <mmacy at nextbsd dot org>
Discussed on: transport@ mailing list
Reviewed by: jtl
MFC after: 1 month
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D8225
- The mean RTT is updated at the end of each congestion epoch, but if we switch
to congestion avoidance within the first epoch (e.g. if ssthresh was primed
from the hostcache), we'll trigger a divide by zero panic in
cubic_ack_received(). Set the mean to the min in cubic_record_rtt() if the
mean is less than the min to ensure we have a sane mean for use in this
situation. This fixes the panic reported by Nick Hibma.
- Adjust conditions under which we update the mean RTT in cubic_post_recovery()
to ensure a low latency path won't yield an RTT of less than 1. This avoids
another potential divide by zero panic when running CUBIC in networks with
sub-millisecond latencies.
- Remove the "safety" assignment of min into mean when we don't update the mean
because of failed conditions. The above change to the conditions for updating
the mean ensures the safety issue is addressed and I feel it is better to keep
our previous mean estimate around if we can't update than to revert to the
min.
- Initialise the mean RTT to 1 on connection startup to act as a safety belt if
a situation we haven't considered and addressed with the above changes were to
crop up in the wild.
Sponsored by: FreeBSD Foundation
Reported and tested by: Nick Hibma
Discussed with: David Hayes <dahayes at swin edu au>
MFC after: 5 weeks
X-MFC with: r216114
algorithm based on the Internet-Draft "draft-rhee-tcpm-cubic-02.txt". It is
implemented as a kernel module compatible with the recently committed modular
congestion control framework.
CUBIC was designed for provide increased throughput in fast and long-distance
networks. It attempts to maintain fairness when competing with legacy NewReno
TCP in lower speed scenarios where NewReno is able to operate adequately. The
paper "CUBIC: A New TCP-Friendly High-Speed TCP Variant" provides additional
detail.
In collaboration with: David Hayes <dahayes at swin edu au> and
Grenville Armitage <garmitage at swin edu au>
Sponsored by: FreeBSD Foundation
Reviewed by: rpaulo (older patch from a few weeks ago)
MFC after: 3 months
