5 ms·

With advent of memristor based memory it'll be possible today (at extremely high cost on the order of a medium nation's GDP) have on the orders of petabytes of

With advent of memristor based memory it'll be possible today (at extremely high cost on the order of a medium nation's GDP) have on the orders of petabytes of what will functionally be RAM. Only ~6-7 tick/tock cycles are necessary for that to expand beyond the address space of 64bit addressing (~10^19).

igravious 12y ago
How long is a tick/tock cycle? A few years? 3 * 7 = 21. So we'd need to prep for going beyond 64bit some time before 2035? Which chimes with the quote At historic rates of growth, it is possible that greater than 64 bits of address space might be required before 2030 that 'unwind' kindly gives in a sister comment. Seems like good forward planning but a little premature, no? These features must come at some cost. Surely you could have a re-vamp sometime around 2025?
- vidarh 12y ago
  Why in the world would you plan a new architecture today, that will take years - easily a decade or more - to gain enough traction to be interesting, only to have to re-vamp it shortly afterwards? We have off the shelf x86 machines today that can fit enough memory to use about 43 bits to address it (at least in theory - depending on DIMM availability; 1TB/2TB is trivially available on the other hand). Now add in size of readily viable storage arrays or even network file systems and expect some people to want to be able to memory map "unreasonably" large files, and suddenly we're into 50+ bits today. It'd seem crazy to me if someone were to start planning a new processor architecture today without planning for addresses greater than 64 bits.
  - JoeAltmaier 12y ago
    64 bits is a hell of a lot larger than 48 bits. You could make the argument that humanity will never need more than 64 bits, no matter how many trillions of years our race exists and uses computers.
    - valarauca1 12y ago
      64ints you mean a 64bit signed dated is massive. Not 64bit address space, 64bits is only ~18exabytes of information. I'm very sure we'll find a need to load that much data into ram eventually.
      - JoeAltmaier 12y ago
        No I meant 64-bit pointers are large enough to handle every piece of memory every manufactured in human history.
        TheLoneWolfling 12y ago
        And at the time of the first 32-bit processors you could potentially say the same about 32-bit pointers.
    - audunw 12y ago
      You dont necessarily have to use every bit of that address space, for a large address space to be useful. The Mill architecture for instance, requires each program to live in its own area of the address space, as this helps make the caches faster (TLB dont have to come before cache). This still leaves a comfortable amount of space left in the 64bit address space.. today. But maybe not in the future
      - JoeAltmaier 12y ago
        Still unlikely there will be enough apps to matter? Every single bit in an address is a doubling of available space, remember.
        vidarh 12y ago
        The number of apps needed for it to matter can be measured in the single digits for there to be demand to pay for it, assuming it's the right single digits... It's quite possible - even likely - that low end systems will not be 128 bits anytime soon. 8 bit microprocessors are still selling in large volumes for embedded use. But we're about to see 64 bit entering phones this year, because it is becoming necessary, or at least more convenient than not. All the evidence is that we're not heading towards a slowdown in growth in storage requirements anytime soon. If anything, the existence of super-computers that are spread over huge clusters instead of being a single, tightly integrated system indicates that there is some level of demand for systems several orders of magnitude larger than the current largest off the shelf systems even today, at the right price. The top end of the market have increased by at least 10 bits over the last 11-12 years alone. At the current storage growth rates, we'll hit the 64 bit limit on single server systems sometime in the next 10-20 years when factoring in memory mapped IO; sooner for single-system-image clusters.

igravious 12y ago

How long is a tick/tock cycle? A few years? 3 * 7 = 21. So we'd need to prep for going beyond 64bit some time before 2035? Which chimes with the quote At historic rates of growth, it is possible that greater than 64 bits of address space might be required before 2030 that 'unwind' kindly gives in a sister comment. Seems like good forward planning but a little premature, no? These features must come at some cost. Surely you could have a re-vamp sometime around 2025?

vidarh 12y ago
Why in the world would you plan a new architecture today, that will take years - easily a decade or more - to gain enough traction to be interesting, only to have to re-vamp it shortly afterwards? We have off the shelf x86 machines today that can fit enough memory to use about 43 bits to address it (at least in theory - depending on DIMM availability; 1TB/2TB is trivially available on the other hand). Now add in size of readily viable storage arrays or even network file systems and expect some people to want to be able to memory map "unreasonably" large files, and suddenly we're into 50+ bits today. It'd seem crazy to me if someone were to start planning a new processor architecture today without planning for addresses greater than 64 bits.
- JoeAltmaier 12y ago
  64 bits is a hell of a lot larger than 48 bits. You could make the argument that humanity will never need more than 64 bits, no matter how many trillions of years our race exists and uses computers.
  - valarauca1 12y ago
    64ints you mean a 64bit signed dated is massive. Not 64bit address space, 64bits is only ~18exabytes of information. I'm very sure we'll find a need to load that much data into ram eventually.
    - JoeAltmaier 12y ago
      No I meant 64-bit pointers are large enough to handle every piece of memory every manufactured in human history.
      - TheLoneWolfling 12y ago
        And at the time of the first 32-bit processors you could potentially say the same about 32-bit pointers.
  - audunw 12y ago
    You dont necessarily have to use every bit of that address space, for a large address space to be useful. The Mill architecture for instance, requires each program to live in its own area of the address space, as this helps make the caches faster (TLB dont have to come before cache). This still leaves a comfortable amount of space left in the 64bit address space.. today. But maybe not in the future
    - JoeAltmaier 12y ago
      Still unlikely there will be enough apps to matter? Every single bit in an address is a doubling of available space, remember.
      - vidarh 12y ago
        The number of apps needed for it to matter can be measured in the single digits for there to be demand to pay for it, assuming it's the right single digits... It's quite possible - even likely - that low end systems will not be 128 bits anytime soon. 8 bit microprocessors are still selling in large volumes for embedded use. But we're about to see 64 bit entering phones this year, because it is becoming necessary, or at least more convenient than not. All the evidence is that we're not heading towards a slowdown in growth in storage requirements anytime soon. If anything, the existence of super-computers that are spread over huge clusters instead of being a single, tightly integrated system indicates that there is some level of demand for systems several orders of magnitude larger than the current largest off the shelf systems even today, at the right price. The top end of the market have increased by at least 10 bits over the last 11-12 years alone. At the current storage growth rates, we'll hit the 64 bit limit on single server systems sometime in the next 10-20 years when factoring in memory mapped IO; sooner for single-system-image clusters.