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
This was discussed between various transport@ members and it was
requested to be reverted and discussed.
Submitted by: kevin
Reported by: lawerence
Reviewed by: hiren
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
tso_segsz pkthdr field during RX processing, and use the information in TCP for
more correct accounting and as a congestion control input. This is only a start,
and an audit of other uses for the data is left as future work.
Reviewed by: gallatin, rrs
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D7564
top 8 bits of the 32 bit signal bit field space for internal use. These private
signals should not be leaked outside of a module.
Given that many algorithm modules use the NewReno hook functions to simplify
their implementation, the obvious place such a leak would show up is in the
NewReno cong_signal hook function.
- Show the full number of significant bits in the signal type definitions in
<netinet/cc.h>.
- Add a bitmask to simplify figuring out if a given signal is in the private or
public bit range.
- Add a sanity check in newreno_cong_signal() to ensure private signals are not
being leaked into the hook function.
Sponsored by: FreeBSD Foundation
Discussed with: David Hayes <dahayes at swin edu au>
MFC after: 1 week
X-MFC with: r215166
somewhere along the way due to mismerging r211464 in our development tree.
- Capture the essence of r211464 in NewReno's after_idle() hook. We don't
use V_ss_fltsz/V_ss_fltsz_local yet which needs to be revisited.
Sponsored by: FreeBSD Foundation
Submitted by: David Hayes <dahayes at swin edu au>
MFC after: 9 weeks
X-MFC with: r215166
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
