32 bit PAE vs 64 bit distro

[RacerBG]

Well in Windows one thing is sure: If you have 4 GB RAM and your hardware can support 64 bit - go for it!

But in Linux...I don't know if I'm the only one but can one 32 bit PAE system be enough for PC with 4GB+ RAM? And if this is possible - then why we have 64 bit versions? The Linux world sometimes confuses me a lot!

[Previous1]

64bit is supposed to offer better ASLR as well as add performance in select applications. Otherwise I'm curious myself - as you have to take in the additional overhead and multiarch-mess.

[nomko]

Today 32-bit CPU's aren't offered anymore. It's 64-bit only what you get in the stores. So, any 32-bit operating system is a dying dinosaur. More and more applications become available for 64-bit systems only. The question should be whther 32-bit PAE is better than 64-bit or why not using 32-bit PAE instead of 64-bit, the question should be when will the support for 32-bit be terminated in favour of 64-bit?

[karlchen]

64bit [...] Otherwise I'm curious myself - as you have to take in the additional overhead and multiarch-mess.

No multiarch mess whatsoever on my 64-bit systems: Ubuntu 12.04.4 "Precise Pangolin" and Mint 13 "Maya". 64-bit software only.

[karlchen]

The question should be whther 32-bit PAE is better than 64-bit or why not using 32-bit PAE instead of 64-bit

No question. Only 64-bit architecture can address more than 4 GB of RAM directly.
32-bit with PAE uses dirty little tricks to address the memory blocks higher than 4 GB, much like the DOS extender used to do so the address RAM above the first MB.

[Previous1]

No multiarch mess whatsoever on my 64-bit systems: Ubuntu 12.04.4 "Precise Pangolin" and Mint 13 "Maya". 64-bit software only.

Good if it works for you.

32-bit with PAE uses dirty little tricks to address the memory blocks higher than 4 GB

In a day-to-day scenario, what's the consequence from these "dirty little tricks"?

[altair4]

I have 16GB of memory on this box and I use the 32-pae version.

At present I have in addition to the host machine running 4 VBox guests running each allocated with 2gb of memory. According to system monitor 5.6 GB of memory are in use.

PAE allows you to access up to 4GB per process. What it will not do is allow access to all 16GB in one process at the same time.

I'm not suggesting anyone else run this way I'm just saying it can be done.

[Previous1]

PAE allows you to access up to 4GB per process. What it will not do is allow access to all 16GB in one process at the same time..

That makes sense. Thanks for clarifying.

[xenopeek]

To clarify, 32 bit vs 64 bit isn't just about instructions being able to process twice the amount of data per operation. These are completely different processor architectures, with 64 bit having a vastly expanded instruction set and additional capabilities. 64 bit architecture is backwards compatible with 32 bit (and 16 bit) architecture--though as already shared it improves upon it through PAE (allowing a 32 bit operating system to address a 64 GiB address space, with 4 GiB addressable per process). Using a 32 bit operating system on a 64 bit processor uses but a small subset of the processor's capabilities.

32 bit architecture, as first introduced on Intel's 80386 processor range, is now 30 years old. Though on the earlier range of Pentium labelled processors Intel expanded this architecture's instruction set and capabilities somewhat (and probably AMD did the same for their range), most software when talking about 32 bit is today compiled for the 30 year old 80386's instruction set. The kernel developers notably have dropped support for the 80386 instruction set (and its limitations) and newer 32 bit kernels require at requires at least processor compatible with Intel's 80486 processor range (now 25 years old).

64 bit architecture was designed 15 years ago, though it took a bit longer for processors with this architecture to become mainstream. It generally is faster for repetitive operations on larger data sets like rendering, encoding, transcoding, archiving, encrypting, and other such operations. A downside on memory limited systems is that is can use on average up to 30% more memory for the same process. It's a trade-off worth it on computers that have at least 4 GiB RAM, perhaps from as low as 2 GiB RAM (I ran a 2 GiB RAM computer with 64 bit Linux for years).

[RacerBG]

So, Xenopeek, you are saying that running 64 bit distro won't hurt even if you don't have 4+ GB RAM?

My only fear about 64 bit is the compatibility with 32 bit and how they are wroking together (32 bit programs and 64 bit programs). Still I smell that 32 bit IS stronger but after a few years it will be minority maybe.

[xenopeek]

You can run most 32 bit programs just fine on 64 bit Linux Mint. Just install the package ia32-libs, which install 32 bit versions of common system libraries. I've never had any unresolvable problems and in most cases here on the forums installing ia32-libs is the solution.

I think one case where you might prefer 32 bit is Wine, at least that's what I recall. I don't use it.

[nomko]

I think one case where you might prefer 32 bit is Wine, at least that's what I recall. I don't use it.

Correct, although Wine doesn't prefer 32-bit, it can only handle 32-bit operating systems and applications. When trying to use 64-bit you get some kind of kernel warning.