[Bloat] Possibly interesting video on atomic clocks

[Bloat] Possibly interesting video on atomic clocks

[Michael Yartys]

Hi

Linus Tech Tips just made a pretty interesting video about atomic clocks in computers and why they're useful. From what I understand, timing is important in networking, and that's why I thought this video might be interesting to this list. One example from the video: facebook managed to increase throughput by x100 in their data centres due to not having to add a 20 ms delay to each request to compensate for drifting clocks. Check it out here: https://www.youtube.com/watch?v=JK3eTGkX6qY

Michael

Re: [Bloat] Possibly interesting video on atomic clocks

[Carsten Bormann]

On 2021-08-24, at 20:00, Michael Yartys via Bloat <bloat@lists.bufferbloat.net> wrote:
> 
> https://www.youtube.com/watch?v=JK3eTGkX6qY

OMG.  Among other things, he says:

A cheap Rubidium clock module has a deviation of less than 1 second in 100 million years (that would be 3e-16!) (1).
Because it’s an atomic clock, it sure must be radioactive (2).
NTP gives you 400 ms deviations (3).

Well, that should be enough to laugh this whole thing off.

However:

PTP is good (a), and support for it is in many chips (b).
It is useful to have a local time reference that is better than a crappy CPU clock crystal (c) (even if a Rubidium oscillator is overkill, in particular if you already have PTP to sync with — go for a cheap OCXO for a start).

Linus’ typical 254,481 views is going to get some attention to the question of precise clocks on computers — that is probably the only good coming from this video, together with complete garbage such as that your computer must be radioactive to give you a fair gaming experience.

Grüße, Carsten