5 ms·

For reference 2^64 = ~10^19.266 I don't think this is unreasonable at all, its unlikely that computers will largely stay the same in the coming years. I believe

For reference 2^64 = ~10^19.266 I don't think this is unreasonable at all, its unlikely that computers will largely stay the same in the coming years. I believe we'll see many changes to how things like mass addressing of data and computing resources is done. Right now our limitations in these regards are addressed by distributed computing and databases, but in a hyper-connected world there may come a time when such huge address space could actually be used. It's an unlikely hypothetical but imagine if fiber ran everywhere, and all computers seamlessly worked together sharing computer power as needed. Even 256 bits wouldn't be out of the question then. And before you say something like that will never happen consider trying to convince somebody from 2009 that in 13 years people would be buying internet money backed by nothing.

est31 4y ago
The extra bits might be used for different things like e.g. in CHERI. The address space is still 64 bits, but there are 64 bits in metadata added to it, so you get a 128 bit architecture.
Tsarbomb 4y ago
Not agreeing or disagreeing for the most part, but in 2009 all of the prerequisite technology for cryptocurrency existed: general purpose computers for the average person, accessible internet, cryptographic algorithms and methods, and cheap storage. For 256 bit computers, we need entirely new CPU architectures and updated ISAs for not just x86/AMD64, but for other archs increasing in popularity such as ARM and even RISC-V. Even then compilers, build tools, and dependant devices with their drivers need updates too. On top of all of this technical work, you have the political work of getting people to agree on new standards and methods.
- mhh__ 4y ago
  256 bits in the case of a worldwide mega-computer would be such a huge departure from current architectures and more importantly latency-numbers that we can barely even speculate about it. It may be of note that hypothetically one can have a soft-ISA 128 bit virtual address (a particularly virtual virtual address) which is JITed down into a narrower physical address by the operating system. This is as far as I'm aware how IBM i works.
  - arthur2e5 4y ago
    For what is worth, 256 / log2(10) is around 77, while the observable universe is estimated to have anywhere from 10^78 to 10^82 atoms. An 256-bit address space, if fully utilized, would produce Asimov’s AC from The Last Question. More realistically though, we would throw away at least half that length like how we are handing out /64 blocks to everyone on IPv6.
masklinn 4y ago
I don’t know it seems excessive to me. I could see the cold storage maybe, with spanning storage pools (by my reckoning there were 10TB drives in 2016 and the largest now are 20, so 16 years from now should be 320 if it keeps doubling, which is 5 orders of magnitude below still). > Right now our limitations in these regards are addressed by distributed computing and databases, but in a hyper-connected world there may come a time when such huge address space could actually be used. Used at the core of the OS itself? How do you propose to beat the speed of light exactly? Because you don’t need a zettabyte-compatible kernel to run a distributed database (or even file system, see ZFS), trying to DMA things on the other side of the planet sounds like the worst possible experience. Hell, our current computers right now are not even close to 64 bit address spaces. The baseline is 48 bits, and x86 and ARM are in the process of extending the address space (to 57 bits for x86, and 52 for ARM).
- alain94040 4y ago
  Thanks to Moore's law, you can assume that DRAM capacity will double every 1-3 years. Every time it doubles, you need one more bit. So if we use 48 bits today, we have 16 bits left to grow, which gives us at least 16 years of margin, and maybe 48 years. (and it could be even longer if you believe that Moore's law is going to keep slowing down).
jmillikin 4y ago
> It's an unlikely hypothetical but imagine if fiber ran everywhere, > and all computers seamlessly worked together sharing computer power > as needed. Even 256 bits wouldn't be out of the question then. You could do this today with 196 bits (128-bit IPv6 address, 64-bit local pointer). Take a look at RDMA, which could be summarized as "every computer's RAM might be any computer's RAM". The question is whether such an address makes sense for the Linux kernel. If your hyper-converged distributed program wants to call `read()`, does the pointer to the buffer really need to be able to identify any machine in the world? Maybe it's enough for the kernel to use 64-bit local pointers only, and have a different address mechanism for remote storage.
Deukhoofd 4y ago
> all computers seamlessly worked together sharing computer power as needed. Even 256 bits wouldn't be out of the question then. This sounds like it would be massively out of scope for Linux. It'd require a complete overhaul of most of its core functionality, and all of its syscalls. While not a completely infeasible idea, it sounds to me like it'd require a completely new designed kernel.

est31 4y ago

The extra bits might be used for different things like e.g. in CHERI. The address space is still 64 bits, but there are 64 bits in metadata added to it, so you get a 128 bit architecture.

Tsarbomb 4y ago

Not agreeing or disagreeing for the most part, but in 2009 all of the prerequisite technology for cryptocurrency existed: general purpose computers for the average person, accessible internet, cryptographic algorithms and methods, and cheap storage. For 256 bit computers, we need entirely new CPU architectures and updated ISAs for not just x86/AMD64, but for other archs increasing in popularity such as ARM and even RISC-V. Even then compilers, build tools, and dependant devices with their drivers need updates too. On top of all of this technical work, you have the political work of getting people to agree on new standards and methods.

mhh__ 4y ago
256 bits in the case of a worldwide mega-computer would be such a huge departure from current architectures and more importantly latency-numbers that we can barely even speculate about it. It may be of note that hypothetically one can have a soft-ISA 128 bit virtual address (a particularly virtual virtual address) which is JITed down into a narrower physical address by the operating system. This is as far as I'm aware how IBM i works.
- arthur2e5 4y ago
  For what is worth, 256 / log2(10) is around 77, while the observable universe is estimated to have anywhere from 10^78 to 10^82 atoms. An 256-bit address space, if fully utilized, would produce Asimov’s AC from The Last Question. More realistically though, we would throw away at least half that length like how we are handing out /64 blocks to everyone on IPv6.

masklinn 4y ago

I don’t know it seems excessive to me. I could see the cold storage maybe, with spanning storage pools (by my reckoning there were 10TB drives in 2016 and the largest now are 20, so 16 years from now should be 320 if it keeps doubling, which is 5 orders of magnitude below still). > Right now our limitations in these regards are addressed by distributed computing and databases, but in a hyper-connected world there may come a time when such huge address space could actually be used. Used at the core of the OS itself? How do you propose to beat the speed of light exactly? Because you don’t need a zettabyte-compatible kernel to run a distributed database (or even file system, see ZFS), trying to DMA things on the other side of the planet sounds like the worst possible experience. Hell, our current computers right now are not even close to 64 bit address spaces. The baseline is 48 bits, and x86 and ARM are in the process of extending the address space (to 57 bits for x86, and 52 for ARM).

alain94040 4y ago
Thanks to Moore's law, you can assume that DRAM capacity will double every 1-3 years. Every time it doubles, you need one more bit. So if we use 48 bits today, we have 16 bits left to grow, which gives us at least 16 years of margin, and maybe 48 years. (and it could be even longer if you believe that Moore's law is going to keep slowing down).

jmillikin 4y ago

> It's an unlikely hypothetical but imagine if fiber ran everywhere, > and all computers seamlessly worked together sharing computer power > as needed. Even 256 bits wouldn't be out of the question then. You could do this today with 196 bits (128-bit IPv6 address, 64-bit local pointer). Take a look at RDMA, which could be summarized as "every computer's RAM might be any computer's RAM". The question is whether such an address makes sense for the Linux kernel. If your hyper-converged distributed program wants to call `read()`, does the pointer to the buffer really need to be able to identify any machine in the world? Maybe it's enough for the kernel to use 64-bit local pointers only, and have a different address mechanism for remote storage.

Deukhoofd 4y ago

> all computers seamlessly worked together sharing computer power as needed. Even 256 bits wouldn't be out of the question then. This sounds like it would be massively out of scope for Linux. It'd require a complete overhaul of most of its core functionality, and all of its syscalls. While not a completely infeasible idea, it sounds to me like it'd require a completely new designed kernel.