src/sys/netinet/khelp, branch release/9.3.0

MFC r239346:

2012-08-21T02:17:06Z

The TCP PAWS fix for kernels with fast tick rates (r231767) changed the TCP timestamp related stack variables to reference ms directly instead of ticks. The h_ertt(4) Khelp module relies on TCP timestamp information in order to calculate its enhanced RTT estimates, but was not updated as part of r231767. Consequently, h_ertt has not been calculating correct RTT estimates since r231767 was comitted, which in turn broke all delay-based congestion control algorithms because they rely on the h_ertt RTT estimates. Fix the breakage by switching h_ertt to use tcp_ts_getticks() in place of all previous uses of the ticks variable. This ensures all timestamp related variables in h_ertt use the same units as the TCP stack and therefore results in meaningful comparisons and RTT estimate calculations. Reported & tested by: Naeem Khademi (naeemk at ifi uio no) Discussed with: bz

Use the full and proper company name for Swinburne University of Technology

2011-04-12T08:13:18Z

throughout the source tree. Requested by: Grenville Armitage, Director of CAIA at Swinburne University of Technology MFC after: 3 days

Import the ERTT (Enhanced Round Trip Time) Khelp module. ERTT uses the

2011-01-24T23:08:38Z

Khelp/Hhook KPIs to hook into the TCP stack and maintain a per-connection, low noise estimate of the instantaneous RTT. ERTT's implementation is robust even in the face of delayed acknowledgements and/or TSO being in use for a connection. A high quality, low noise RTT estimate is a requirement for applications such as delay-based congestion control, for which we will be importing some algorithm implementations shortly. In collaboration with: David Hayes and Grenville Armitage Sponsored by: FreeBSD Foundation Reviewed by: bz and others along the way MFC after: 3 months