Hi Stephen and Lachlan, Thanks for pointing out and fixing this bug.
For the max RTT problem, I have considered it also and I have some idea on improve it. I also have some other places to improve. I will summarize all my new ideas and send you an update. For me to change it, could you please give me a link to download to latest source codes for the whole congestion control module in Linux implementation, including the general module for all algorithms, and the implementation for specific algorithms like TCP-Illinois and H-TCP? Thanks for the help! -Shao -----Original Message----- From: Stephen Hemminger [mailto:[EMAIL PROTECTED] Sent: Wednesday, November 28, 2007 4:44 PM To: Lachlan Andrew Cc: David S. Miller; Herbert Xu; [EMAIL PROTECTED]; Douglas Leith; Robert Shorten; netdev@vger.kernel.org Subject: Re: [PATCH] tcp-illinois: incorrect beta usage Lachlan Andrew wrote: > Thanks Stephen. > > A related problem (largely due to the published algorithm itself) is > that Illinois is very aggressive when it over-estimates the maximum > RTT. > > At high load (say 200Mbps and 200ms RTT), a backlog of packets builds > up just after a loss, causing the RTT estimate to become large. This > makes Illinois think that *all* losses are due to corruption not > congestion, and so only back off by 1/8 instead of 1/2. > > I can't think how to fix this except by better RTT estimation, or > changes to Illinois itself. Currently, I ignore RTT measurements when > sacked_out != 0 and have a heuristic "RTT aging" mechanism, but > that's pretty ugly. > > Cheers, > Lachlan > > Ageing the RTT estimates needs to be done anyway. Maybe something can be reused from H-TCP. The two are closely related. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
