3 ms·

If you're on a 64bit machine storing 32bit ints, this will decrease the node size from 32 + 64 + 64 = 160 to 32 + 64 = 96, so you should be able to store 66% mo

If you're on a 64bit machine storing 32bit ints, this will decrease the node size from 32 + 64 + 64 = 160 to 32 + 64 = 96, so you should be able to store 66% more data. edit: In fact, when do you ever really need to store particularly large objects in something like a linked-list? It seems like you can always get some relatively small reference value to the data (eg, a pointer) and store that in your list instead of storing your large objects themselves.

deleted 14y ago
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benwr 14y ago
If you're storing references to larger objects, your larger objects are what's taking up the space, which I think was the point (66% more pointers are useless if you can't also store 66% more of the objects they point to). Also, I think on a 64-bit machine with common DDR SDRAM, a memory location is 64 bits wide, no matter the size of the integer contained there. Not sure about this, however.
- zanny 14y ago
  Most modern architectures like AMD64 use 40 bit memory references in the CPU, but write them as 64 bit to memory. That is why they have much lower addressable memory than the logical limit.
  - DiabloD3 14y ago
    I think Bulldozer and Ivy Bridge are both 48, but I'm not going to dive into 500 page PDFs to find out.
    - zanny 14y ago
      Maybe, I just remember that number from powerPC / ARM back in my assembly class in 2010.
- zurn 14y ago
  Some compilers/runtimes support pointer compression (eg. https://wikis.oracle.com/display/HotSpotInternals/CompressedOops https://wikis.oracle.com/display/HotSpotInternals/Compressed...)
- DennisP 14y ago
  Not if you're storing lots of references to the same object, which is what I'm often doing. And my objects are really small anyway.
- alecbenzer 14y ago
  > If you're storing references to larger objects, your larger objects are what's taking up the space, which I think was the point (66% more pointers are useless if you can't also store 66% more of the objects they point to). Right, of course... > I really don't know all that much about architecture (yet), so that's totally possible, and I might be wrong about the 66% thing I guess. edit: Actually, about the whole more objects thing, there might be some strange use case where you only have a few objects but are storing multiple references to them in a list. But yeah, in general, the benefit goes down with larger objects.

deleted 14y ago

[deleted]

benwr 14y ago

If you're storing references to larger objects, your larger objects are what's taking up the space, which I think was the point (66% more pointers are useless if you can't also store 66% more of the objects they point to). Also, I think on a 64-bit machine with common DDR SDRAM, a memory location is 64 bits wide, no matter the size of the integer contained there. Not sure about this, however.

zanny 14y ago
Most modern architectures like AMD64 use 40 bit memory references in the CPU, but write them as 64 bit to memory. That is why they have much lower addressable memory than the logical limit.
- DiabloD3 14y ago
  I think Bulldozer and Ivy Bridge are both 48, but I'm not going to dive into 500 page PDFs to find out.
  - zanny 14y ago
    Maybe, I just remember that number from powerPC / ARM back in my assembly class in 2010.
zurn 14y ago
Some compilers/runtimes support pointer compression (eg. https://wikis.oracle.com/display/HotSpotInternals/CompressedOops https://wikis.oracle.com/display/HotSpotInternals/Compressed...)
DennisP 14y ago
Not if you're storing lots of references to the same object, which is what I'm often doing. And my objects are really small anyway.
alecbenzer 14y ago
> If you're storing references to larger objects, your larger objects are what's taking up the space, which I think was the point (66% more pointers are useless if you can't also store 66% more of the objects they point to). Right, of course... > I really don't know all that much about architecture (yet), so that's totally possible, and I might be wrong about the 66% thing I guess. edit: Actually, about the whole more objects thing, there might be some strange use case where you only have a few objects but are storing multiple references to them in a list. But yeah, in general, the benefit goes down with larger objects.