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Maybe a stupid question and I've missed something, but why even bother telling us they're using 32GBs RAM for benchmarking if they're using 32-bit Ubuntu? Just

Maybe a stupid question and I've missed something, but why even bother telling us they're using 32GBs RAM for benchmarking if they're using 32-bit Ubuntu? Just to be totally transparent? Is Windows a 32-bit W7 too?

rmk2 14y ago
I'm not sure if this is the right answer or not, but the Linux kernel has supported PAE[1] for ages, which allows for more than 4GB of RAM in a 32-bit OS (though it remains unusable by a single process, if I understood that correctly). Maybe someone else with a better understanding of the 32bit/64bit differences can chime in. [1]: https://en.wikipedia.org/wiki/Physical_Address_Extension https://en.wikipedia.org/wiki/Physical_Address_Extension
- kbolino 14y ago
  PAE would definitely enable them to use all 32GBs of physical memory. Both Windows and Linux have PAE support, but non-server editions of Windows still limit the physical address space to 4GB (although this might seem to make PAE support pointless, there are other advantages of PAE, like the NX/XD bit used for DEP). You are also correct that the per-process limit of 4GB of virtual memory is not affected by PAE. In case the advantages of PAE once again seem pointless, remember that a system can execute multiple 32-bit programs each with its own independent address space, so you can have, in theory, eight programs each using its own 4GB on a 32GB system without running out of memory. In practice, the platform imposes a limit of <4GB for physical memory, with the remainder used for legacy support and hardware DMA. Also, the operating system imposes a limit of <4GB for virtual memory, with the remainder used by the kernel.
Splines 14y ago
I've only dabbled in Linux, but what's the advantage of using 32-bit Ubuntu? Why not the 64-bit version? Especially in the Linux world where you deal with binaries less-often compared to Windows. Is it because of the video card drivers?
- kbolino 14y ago
  All things being equal, on 32-bit systems, pointers are 32 bits wide, and on 64-bit systems, pointers are 64 bits wide. So if your program previously used X bytes of memory for storing pointers, it would now use 2X bytes. Depending on how pointer-heavy your memory usage is, the impact of this change could be anywhere from negligible to significant. This is part of the reason why games remain 32-bit on Windows as well (that, and compatibility with 32-bit versions of the OS). However, there are, on x86 at least, other reasons to go 64-bit, perhaps the most prominent of which being the availability of additional general-purpose registers (8 more, to be precise). An ABI for Linux has been proposed called x32 that would run 64-bit code but use only 32 bits for pointers. This would re-impose the 4GB per-process memory limitation but still allow the use of other 64-bit-only features. AFAIK, x32 programs are not compatible with x64 libraries, and vice versa, though.
IsTom 14y ago
I don't think this game will use 3 GBs of RAM. If that's the case it doesn't matter that much.
danielweber 14y ago
Am I expected to have 32GB of RAM to play Steam games? Even my office computer only has 8GB of RAM. I've stayed out of PC gaming for a long time because it seemed to have a fetish for spending lots of money on graphics cards. EDIT: Am I being downvoted because it's stupid to ask about 32GB because obviously every Real Gamer already has that, or because it's stupid to ask about 32GB because obviously no one needs that?
- alexholehouse 14y ago
  I suspect you're being downvoted because no, you're definitely not expected to have 32GB of RAM. I'd imagine the example just uses a high-end config to show that it's not a hardware issue bottle necking performance (or, rather, not a hardware issue you'd normally run into - e.g. not enough memory, too slow CPU etc). Downvoting seems somewhat over the top, I'd say.

rmk2 14y ago

I'm not sure if this is the right answer or not, but the Linux kernel has supported PAE[1] for ages, which allows for more than 4GB of RAM in a 32-bit OS (though it remains unusable by a single process, if I understood that correctly). Maybe someone else with a better understanding of the 32bit/64bit differences can chime in. [1]: https://en.wikipedia.org/wiki/Physical_Address_Extension https://en.wikipedia.org/wiki/Physical_Address_Extension

kbolino 14y ago
PAE would definitely enable them to use all 32GBs of physical memory. Both Windows and Linux have PAE support, but non-server editions of Windows still limit the physical address space to 4GB (although this might seem to make PAE support pointless, there are other advantages of PAE, like the NX/XD bit used for DEP). You are also correct that the per-process limit of 4GB of virtual memory is not affected by PAE. In case the advantages of PAE once again seem pointless, remember that a system can execute multiple 32-bit programs each with its own independent address space, so you can have, in theory, eight programs each using its own 4GB on a 32GB system without running out of memory. In practice, the platform imposes a limit of <4GB for physical memory, with the remainder used for legacy support and hardware DMA. Also, the operating system imposes a limit of <4GB for virtual memory, with the remainder used by the kernel.

Splines 14y ago

I've only dabbled in Linux, but what's the advantage of using 32-bit Ubuntu? Why not the 64-bit version? Especially in the Linux world where you deal with binaries less-often compared to Windows. Is it because of the video card drivers?

kbolino 14y ago
All things being equal, on 32-bit systems, pointers are 32 bits wide, and on 64-bit systems, pointers are 64 bits wide. So if your program previously used X bytes of memory for storing pointers, it would now use 2X bytes. Depending on how pointer-heavy your memory usage is, the impact of this change could be anywhere from negligible to significant. This is part of the reason why games remain 32-bit on Windows as well (that, and compatibility with 32-bit versions of the OS). However, there are, on x86 at least, other reasons to go 64-bit, perhaps the most prominent of which being the availability of additional general-purpose registers (8 more, to be precise). An ABI for Linux has been proposed called x32 that would run 64-bit code but use only 32 bits for pointers. This would re-impose the 4GB per-process memory limitation but still allow the use of other 64-bit-only features. AFAIK, x32 programs are not compatible with x64 libraries, and vice versa, though.

IsTom 14y ago

I don't think this game will use 3 GBs of RAM. If that's the case it doesn't matter that much.

danielweber 14y ago

Am I expected to have 32GB of RAM to play Steam games? Even my office computer only has 8GB of RAM. I've stayed out of PC gaming for a long time because it seemed to have a fetish for spending lots of money on graphics cards. EDIT: Am I being downvoted because it's stupid to ask about 32GB because obviously every Real Gamer already has that, or because it's stupid to ask about 32GB because obviously no one needs that?

alexholehouse 14y ago
I suspect you're being downvoted because no, you're definitely not expected to have 32GB of RAM. I'd imagine the example just uses a high-end config to show that it's not a hardware issue bottle necking performance (or, rather, not a hardware issue you'd normally run into - e.g. not enough memory, too slow CPU etc). Downvoting seems somewhat over the top, I'd say.