Gettys: Traditional AQM is not enough

Posted Jul 11, 2013 19:00 UTC (Thu) by jg (guest, #17537)
In reply to: Gettys: Traditional AQM is not enough by mtaht
Parent article: Gettys: Traditional AQM is not enough

Consensus that fq_codel has been tested enough. We'll probably have that discussion at LPC at the end of the summer.

Note the fq_codel qdisc not a panacea: don't believe that just because it becomes the default, all your bufferbloat problems will go away.

There is lots of driver work left to do, particularly for 802.11, DSL, and cellular to name a few. Some of these drivers are closed source, and getting it deployed everywhere is going to take a long time even after they've been fixed.

Gettys: Traditional AQM is not enough

Posted Jul 11, 2013 19:52 UTC (Thu) by dlang (guest, #313) [Link] (1 responses)

> Consensus that fq_codel has been tested enough.

Exactly, changing the default is a big step. fq_codel hasn't even been out long enough to make it in to any of the Enterprise distros as an option, let alone having any of them turn it on by default.

As such, it's probably premature for the upstream kernel to turn it on by default.

Gettys: Traditional AQM is not enough

Posted Jul 11, 2013 20:02 UTC (Thu) by jg (guest, #17537) [Link]

Heh. If we wait for enterprise distros to do anything, Linux slows to a crawl. It's not as if enterprise guys don't go through their own cycle of configuration testing and ship kernel.org kernels unchanged and untested.

The big point in favor of changing the default in kernel.org (after more a year upstream in kernel.org, I'll note) is just how terrible PFIFO_FAST turns out to be as shown by Toke's CDF plot in that blog entry and all the other measurements we've made. We're orders of magnitude from where we know we can be. The improvement is *not* subtle.

But changing a default *is* a serious step, and until we get everyone in a room to talk it through, expressing all the pros and cons and concerns, it's not a decision to be taken lightly.