6 ms·

How much time does moving to 64 nits buy us? it's likely considerable, but I cant help but imagine a time when we have to address this problem for a third time.

How much time does moving to 64 nits buy us? it's likely considerable, but I cant help but imagine a time when we have to address this problem for a third time. It seems to me like a more robust solution is possible.

jorams 8y ago
While 32-bit time_t lasts for roughly 68 years, 64-bit time_t lasts for roughly 292270958501 years.
- perl4ever 8y ago
  Well, what if you want to measure small fractions of a second? If your timestamps have significantly higher resolution than a nanosecond, you've used up your extra 32 bits. And there is technology that operates on much shorter intervals, like about 10^-18 seconds. While it may not be very relevant today, if you really want to future proof things for the next 1000 years, I think you need around 90 bits or more. "12 attoseconds is the world record for shortest controllable time" https://phys.org/news/2010-05-attoseconds-world-shortest.html https://phys.org/news/2010-05-attoseconds-world-shortest.htm... After further consideration, the ultimate timestamp would be able to denote any point in time measured in Planck units (10^-44 seconds) between the beginning of the universe and its ultimate heat death in about 3 x 10^21 seconds. Therefore 218 bits should be enough for anyone.
ecma 8y ago
Really? I'm not sure if this is bait or not, but 64b time_t extends the epoch over 200 billion years into the future. I figure we'll handle it in Linux 7.0 or 8.0 at the earliest :P
- lucb1e 8y ago
  It's probably not bait. It's easy to intuitively think 64 bits is only double. I do these calculations regularly as security professional (password strength for example) but not everyone does.
  - beatgammit 8y ago
    Well, 64 bits is often used with nanoseconds, and 32 bits is in seconds, so it's a bit more complex than it seems.
omegaham 8y ago
The 64 bit clock will overflow about 292 billion years from now. That's long enough for me. --- Worrying about 64-bit time overflow is like worrying about IPv6 address exhaustion.
- adrianN 8y ago
  Running out of IPv6 addresses is more likely than you think: https://ripe77.ripe.net/archives/video/2287/ https://ripe77.ripe.net/archives/video/2287/
- emmelaich 8y ago
  I'm going to set my cryogenic wake-up for then and make a whole bunch of money.
  - akiselev 8y ago
    Be careful, it the cryogenic controller might overflow and wake you up right after the big bang!
- monocasa 8y ago
  > Worrying about 64-bit time overflow is like worrying about IPv6 address exhaustion. And for those following along at home IPV6 is a 128 bit value. ~2^93 is enough to individually address every subatomic particle on Earth.
  - segfaultbuserr 8y ago
    > ~2^93 is enough to individually address every subatomic particle on Earth. IPv6 address exhaustion is very unlikely, but it's more likely than some may have thought about. Only 64-bit of the 128-bit address space was fully utilized, it means the utilization rate is less than 0.0000000000000000055%. And no, it's not a bug, it's a feature. The huge address space was intended to make address assignment, configuration, and routing easier. That is, in the real world, the first 64-bit part becomes the network identifier, and the last 64-bit becomes the device identifier. Ideally, everyone's home, business, institution, datacenter, etc, will get a unique, globally routable 64-bit network prefix. So no, every subatomic particle on Earth will not get its own IPv6 address. But, everyone of the 7 billion people on Earth can have prefixes for their 263,524,915 personal computer networks.

jorams 8y ago

While 32-bit time_t lasts for roughly 68 years, 64-bit time_t lasts for roughly 292270958501 years.

perl4ever 8y ago
Well, what if you want to measure small fractions of a second? If your timestamps have significantly higher resolution than a nanosecond, you've used up your extra 32 bits. And there is technology that operates on much shorter intervals, like about 10^-18 seconds. While it may not be very relevant today, if you really want to future proof things for the next 1000 years, I think you need around 90 bits or more. "12 attoseconds is the world record for shortest controllable time" https://phys.org/news/2010-05-attoseconds-world-shortest.html https://phys.org/news/2010-05-attoseconds-world-shortest.htm... After further consideration, the ultimate timestamp would be able to denote any point in time measured in Planck units (10^-44 seconds) between the beginning of the universe and its ultimate heat death in about 3 x 10^21 seconds. Therefore 218 bits should be enough for anyone.

ecma 8y ago

Really? I'm not sure if this is bait or not, but 64b time_t extends the epoch over 200 billion years into the future. I figure we'll handle it in Linux 7.0 or 8.0 at the earliest :P

lucb1e 8y ago
It's probably not bait. It's easy to intuitively think 64 bits is only double. I do these calculations regularly as security professional (password strength for example) but not everyone does.
- beatgammit 8y ago
  Well, 64 bits is often used with nanoseconds, and 32 bits is in seconds, so it's a bit more complex than it seems.

omegaham 8y ago

The 64 bit clock will overflow about 292 billion years from now. That's long enough for me. --- Worrying about 64-bit time overflow is like worrying about IPv6 address exhaustion.

adrianN 8y ago
Running out of IPv6 addresses is more likely than you think: https://ripe77.ripe.net/archives/video/2287/ https://ripe77.ripe.net/archives/video/2287/
emmelaich 8y ago
I'm going to set my cryogenic wake-up for then and make a whole bunch of money.
- akiselev 8y ago
  Be careful, it the cryogenic controller might overflow and wake you up right after the big bang!
monocasa 8y ago
> Worrying about 64-bit time overflow is like worrying about IPv6 address exhaustion. And for those following along at home IPV6 is a 128 bit value. ~2^93 is enough to individually address every subatomic particle on Earth.
- segfaultbuserr 8y ago
  > ~2^93 is enough to individually address every subatomic particle on Earth. IPv6 address exhaustion is very unlikely, but it's more likely than some may have thought about. Only 64-bit of the 128-bit address space was fully utilized, it means the utilization rate is less than 0.0000000000000000055%. And no, it's not a bug, it's a feature. The huge address space was intended to make address assignment, configuration, and routing easier. That is, in the real world, the first 64-bit part becomes the network identifier, and the last 64-bit becomes the device identifier. Ideally, everyone's home, business, institution, datacenter, etc, will get a unique, globally routable 64-bit network prefix. So no, every subatomic particle on Earth will not get its own IPv6 address. But, everyone of the 7 billion people on Earth can have prefixes for their 263,524,915 personal computer networks.