Why is the 32-bit version recommended?

[Guest]

The download options says the 32-bit version is recommended.

Is this just because the 64-bit version is not necessary for general work, or is there a significant down-side to the 64-bit version? (eg lack of driver support).

The main software I want to run (Salome-Meca) recommends 64-bit.

[Ole Juul]

Re: Why is the 32-bit version recommended?

I'm sure there are more reasons for recommending one or the other, but I don't think it makes a lot of difference in most cases. There are some things you might consider. You can generally only use 3MB memory if you are using 32 bit. If you have, or want to take advantage of more, then use 64 bit. Another possible consideration would be if you want to run MS-Windows applications. I think Wine is difficult or buggy under 64 bit.

I don't know much about Salome-Meca, but it looks like something which might benefit from a wider data path and more ram - so 64 bit.

[ardvark71]

Re: Why is the 32-bit version recommended?

Hi Brett...

Welcome to the forums

Along with what Ole has said, I've also encountered the extremely rare (only happened once or twice) 32 bit program that required 32 bit specifically. As another example, if you install the 64 bit version of Kubuntu and you go to install a copy of Opera, you will need to install the 64 bit version. If you want flash capabilities with Opera, you will need to locate and install the 64 bit version of flash player for Linux, which I found a little bit difficult but managed to do it.

Overall, I've had no real problems with the 64 bit version of Kubuntu, other than the routine (but not everytime) lockup everytime I boot Kubuntu, due to, I suspect, my video driver. I've experienced no problems in connection with everyday use...and I use it almost every single day.

Regards...

[sasaz]

Re: Why is the 32-bit version recommended?

Deleted.

[Ole Juul]

Re: Why is the 32-bit version recommended?

Oh dear, I think we're getting confusing here. I'm no expert, but I can quote a couple of things from the net:

By definition, a 32-bit processor uses 32 bits to refer to the location of each byte of memory. 2^32 = 4.2 billion, which means a memory address that's 32 bits long can only refer to 4.2 billion unique locations (i.e. 4 GB).

From other readings I see that its actually less than 4GB in practice, its more like 3.37gig because it's an 80x86 architecture limitation. That's why I quoted the figure of 3GB which is commonly used in this case.

That said, there is such a thing as a PAE enabled kernel. That will apparently add the ability to address more memory. However I believe there are some limitations.

Processors with 64 bit ability have been standard for a long time now. Software however, is just now catching up. People who run 64 bit software exclusively don't appear to have any complaints - in fact the contrary.

[wizard10000]

Re: Why is the 32-bit version recommended?

Oh dear, I think we're getting confusing here. I'm no expert, but I can quote a couple of things from the net:

From other readings I see that its actually less than 4GB in practice, its more like 3.37gig because it's an 80x86 architecture limitation. That's why I quoted the figure of 3GB which is commonly used in this case.

That said, there is such a thing as a PAE enabled kernel. That will apparently add the ability to address more memory. However I believe there are some limitations.

Processors with 64 bit ability have been standard for a long time now. Software however, is just now catching up. People who run 64 bit software exclusively don't appear to have any complaints - in fact the contrary.

caution: hardware geek stuff follows. you've been warned

A 32-bit kernel can allocate each process 3GB for user space and 1GB for kernel space - even with PAE enabled, so a 32-bit process running in userspace only gets 3GB of memory no matter how much RAM is installed.

The reason a 32-bit kernel only shows somewhere around 3.3GB of RAM rather than 4GB is that hardware registers take up a fair bit of that 4GB - but it doesn't become an issue unless you've got 4GB of RAM - since you've only got 4GB of address space the amount of RAM the processor can address is reduced by hardware registers that the CPU must access - which would be outside of installed RAM on a machine with 3GB or less memory.

*Some* applications run faster on a 64-bit system because if the processor needs to deal with a word longer than 32 bits it takes extra steps on a 32-bit chip to assemble the word. Video rendering is one application that runs quicker on a 64-bit system than on a 32-bit system.

[sasaz]

Re: Why is the 32-bit version recommended?

Deleted.

[Ole Juul]

Re: Why is the 32-bit version recommended?

@sasaz: I'm sure you know much more about this than I do. I'm just using the default memory manager. I'm curious though, how would I implement a memory manager in Kubuntu which has a 2GB ram usage limit, and what would be the advantage of that?