dis-sys

look at that photo on the top, simply a piece of art. just incredible.

yes, 1m for every 3.3ns error, we all know that.

the problem is those GPS vendors only provide long term average error for their products, there is upper bound guarantee at all.

My preyer are with those brave rats who died for the peace of mankind.

wondering is there any upper bound on the error, e.g. is it possible to ever have a timing error of say 100 microsecond seconds.

A quick question related to this blog -

they mentioned that most modern NICs have hardware timestamp capabilities, that is consistent with what I saw. The question is what is the availability of those PTP ready & enabled routers/switches capable of acting as a Transparent Clock? I have two concerns, most of existing routers/switches are not PTP ready, even for those ones with PTP capabilities, its PTP related features may not be enabled in production. Any experience or numbers to share? thanks!

Nice tech blog, really love it.

From my understanding, basically this new iteration is better then their previous generation chrony based one because the uncertainty in the One Way Delay calculation is largely removed by having those Transparent Clocks capable of reporting their queuing delays. Basically the asymmetry of the delays are gone?

Personally, I don't think Chrony should be considered as a NTP implementation as clearly it can utilize those PTP hardware timestamps as well and those hardware timestamps are the "secret sauce" of PTP's high accuracy. With those PTP enabled switches, together with the fact that Chrony can already send NTP packages as PTP packages, surely Chrony can leverage such new capabilities as well with some reasonable updates.

> Wait until you hear about the leap years! They insert a whole day, often right in the middle of the work week!

That is pretty fine tuned given they only insert a full day. ;)

In Chinese lunar calendar, and probably other calendars as well, they insert a full month known as the leap month. Yes, you hear me right, 13 months in such leap years.

> Too bad there weren't any computers around at the time or software developers might have convinced Julius Caesar what a disaster and source of bugs that will be for centuries to come. He might have dropped the whole idea.

Indeed. Such 2000 years old garbage is just not very compatible with modern way of life in which lots of things are being changed. From memory, in a few years, the definition of a second will also be reviewed by the international community. The current definition based on some funny behavior of Caesium atom is no longer the best. UTC is another drama deserve to have more care.

In 2022, there are not many international matters that can be agreed upon by US, EU and China at the same time. Getting rid of this stupid leap second disaster is one of those rare ones. US, EU and China all agreed that leap second should be eliminated. It is a disaster.

The whole leap second disaster is just beyond imagination - inserting a full second into the system during business hours in Asia when some of the world's largest exchanges are in trading session! When there are hundreds of millions time sensitive devices manufactured by tens of thousands different vendors at vastly different skill levels!

When compared with this leap second invention, Y2K problem is so harmless.

Incredible, hope your sister's remission to be a complete & permanent one.

Literally curing cancer, just incredible.

great story, for me another interesting part is that lots of those tools/utils used in their dev work were copied from that dude's home, surely that is very reproducible & auditable.

I used to pay $800-1,000 a pair, then I heard that the exact same glasses from the exact same factory just without that fancy logo costs you about $100 a pair. Bought a few of them, never looked back.

People need to accept that you get ripped off all the time, it just a normal part of everyday life. when you think a $5 walmart tshirt is cheap, well, the factory gets probably 50c.

> like millions of others

Including Xi Jinping.

Other than the annual university entrance exam and buying properties, Hukou is no longer enforced. The real difference only exists for tier-1 mega cities like Beijing and Shanghai, 97% Chinese don't live there.