[182977] in North American Network Operators' Group
Re: Did *bufferbloat* cause the 2010 flashcrash?
daemon@ATHENA.MIT.EDU (Harlan Stenn)
Thu Aug 6 13:55:28 2015
X-Original-To: nanog@nanog.org
To: nanog@nanog.org
From: Harlan Stenn <stenn@nwtime.org>
Date: Thu, 6 Aug 2015 10:55:24 -0700
In-Reply-To: <CAP-guGWCZyr8tAVtdwC7a_r4cTFXkkBVSj+tm5f-kysvYXCgfQ@mail.gmail.com>
Errors-To: nanog-bounces@nanog.org
In 8/6/15 10:44 AM, William Herrin wrote:
> The intermediate cause of the problem was propagation delay (including
> buffer bloat) which induced an oscillating set of states in the
> trading software.
>
> The root cause was a flipping jassack trying to out-time his
> competitors by assuming a degree of instantaneity which proved untrue.
> Don't do that. Don't make assumptions about network timing. You can
> count on being wrong. If timing matters to your application, find a
> way to continuously measure.
Similar things happen when folks decide they are going to twiddle the
knobs of NTP's behavior. NTP works locally, and gets/provides
information globally. More or less. When folks decide to make a change
in its core behavior, the usually don't consider how those changes will
affect anybody else.
I know enough about this to know I don't know anywhere near enough about
it, so I leave the knobs alone.
--
Harlan Stenn <stenn@nwtime.org>
http://networktimefoundation.org - be a member!
