[Bloat] TCP BBR paper is now generally available

Steinar H. Gunderson sgunderson at bigfoot.com
Fri Dec 2 17:40:06 EST 2016

On Fri, Dec 02, 2016 at 05:22:23PM -0500, Neal Cardwell wrote:
> Of course, if we find important use cases that don't work with BBR, we will
> see what we can do to make BBR work well with them.

I have one thing that I _wonder_ if could be BBR's fault: I run backup over
SSH. (That would be tar + gzip + ssh.) The first full backup after I rolled
out BBR on the server (the one sending the data) suddenly was very slow
(~50 Mbit/sec); there was plenty of free I/O, and neither tar nor gzip
(well, pigz) used a full core. My only remaining explanation would be that
somehow, BBR didn't deal well with the irregular stream of data coming from
tar. (A wget between the same machines at the same time gave 6-700 Mbit/sec.)

I will not really blame BBR here, since I didn't take a tcpdump or have time
to otherwise debug properly (short of eliminating the other things I already
mentioned); most likely, it's something else. But if you've ever heard of
others with similar issues, consider this a second report. :-)

/* Steinar */
Homepage: https://www.sesse.net/

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