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codergeek 01-07-2013 02:57 PM

Adding more ram. Should I stay with a 32 bit distro or go with a 64 bit distro
 
Hi,

I am going to add memory to my computer. Right now, I have 4GB of ram.

Can I still use a 32 bit distro if I increase my memory. I read somewhere that once you go over 4GB of ram, a 64 bit distro is recommended. Anyway, I prefer to use a 32 bit distro.

If I decide to stay with a 32 bit distro with a system of 8GB ram will there be any issues? Thanks

johnsfine 01-07-2013 03:07 PM

With a PAE kernel, a 32-bit distro with 8GB should be no problem.

I prefer a 64-bit distro, but I don't think the change from 4GB to 8GB is a reason to change from 32-bit to 64-bit.

But why do you want to change from 4GB to 8GB?

Most ordinary uses of Linux work just fine with 4GB and won't work noticeably better with 8GB. Things like video editing that work better with 8GB than 4GB also work better with 64-bit than 32-bit (and 64-bit is better for those things even if you only have 4GB).

There are some uses of Linux for which 8GB is significantly better than 4GB without 64-bit being better than 32-bit. But I think such uses are rare.

I'm still not saying a switch from 4GB to 8GB is a good reason to switch from 32-bit to 64-bit, especially if you have no compelling reason to switch from 4GB to 8GB. But if you do have a good reason to switch from 4GB to 8GB, telling us that reason might give you a more informed answer on whether you ought to switch to 64-bit.

Quote:

Originally Posted by codergeek (Post 4864866)
If I decide to stay with a 32 bit distro with a system of 8GB ram will there be any issues?

You know the basics, right? With 32-bit any one process can use up to 3GB of virtual memory. The pages of that virtual memory can be scattered anywhere across your 8GB of physical ram and disk. So multiple processes, plus the kernel, plus file caching may make just as good use of 8GB in 32-bit as they could in 64-bit. But if you want to run one very large process, in 32-bit it is limited to 3GB virtual memory no matter how much physical ram you have.

codergeek 01-07-2013 03:21 PM

thanks for the response johnsfine

I do alot of multimedia encoding in linux and this is why I want more memory. Also, it's hard to tell if an app is 64 bit ready or not, so to be safe, I want to use a 32 bit distro. I never had used a 64 bit distro before, maybe I'll give it a try and if certain apps don't work well with it, then I'll go back to 32 bit.

BTW, do you or anyone know If a 64 bit distro packages only 64 bit apps in both the system and the repositories or is there both 32 and 64 bit apps?

johnsfine 01-07-2013 03:29 PM

Quote:

Originally Posted by codergeek (Post 4864878)
I do alot of multimedia encoding in linux and this is why I want more memory.

multimedia encoding is the kind of thing one would expect to be significantly faster in 64-bit than in 32-bit, even if you have only 1 or 2 GB. But whether it is really faster depends on internal details of the programs that aren't very easy to predict. So you won't really know until you try. It may also depend on the L2 cache size of your CPU (a small L2 cache makes many 64-bit operations slower than 32-bit, which balances the operations that are always faster in 64-bit to net to no difference for many systems).

Quote:

Also, it's hard to tell if an app is 64 bit ready or not
Virtually all open source is 64 bit ready.

Almost all 64-bit distributions are "multilib" meaning they run 32-bit applications at least as well (generally a little better) than a 32-bit distribution. A 32-bit application may be significantly harder to install on a 64-bit distribution (a lot of dependency issues that are automatic for the native size require manual attention for the alternate size). But once correctly installed, there should be no issues at all with running a 32-bit app in 64-bit Linux.

codergeek 01-07-2013 03:33 PM

OK, thanks again for the extra info

+1 rep

johnsfine 01-07-2013 03:37 PM

Quote:

Originally Posted by codergeek (Post 4864878)
BTW, do you or anyone know If a 64 bit distro packages only 64 bit apps in both the system and the repositories or is there both 32 and 64 bit apps?

I'm not sure I understand the question. A related answer depends on whether it is a Debian based distribution (such as Ubuntu) or a Red Hat based distribution (such as OpenSuse).

In Red Hat based distributions, you can easily specify a 32-bit package when selecting a package you want to install. All the directories are the same between the installation of a 32-bit package on a 64-bit system vs. the same package on a 32-bit system.

In Debian based distributions, the directories for .so files are different for a 32-bit package installed on a 32-bit system vs. the same package installed on a 64-bit system. For an app without any .so file, you might be able to directly install a 32-bit package on 64-bit. For a package of common .so files most distributions offer a repacked version (32 bit .so files specifically packaged for 64-bit systems). For in between cases (uncommon .so files) you may need to unpack the package manually and drop the files into systematically different directories from where the package says they should go.

codergeek 01-07-2013 03:48 PM

Hi johnsfine

I think you answered my question with your answer below
Quote:

Virtually all open source is 64 bit ready.

Almost all 64-bit distributions are "multilib" meaning they run 32-bit applications at least as well (generally a little better) than a 32-bit distribution.
Anyway, I am going to try a 64 bit distro for the first time and see what happens. But, I believe it should do well on my system. Thanks again johnsfine :)

Mark1986 01-18-2013 12:59 AM

Hi,

I hope I am not too late with giving this response. (Or maybe you already use it.)

When I am unsure how my system will react to certain change, I create a virtual machine. On that virtual machine I make the changes and see what happens.

I hope this helps you.

TobiSGD 01-18-2013 03:50 AM

The problem here would be that the OP is running a 32 bit system, so he can't give enough memory to the VM to test the effects of more RAM on 32 and 64 bit systems.

BoraxMan 01-19-2013 05:23 AM

I went from 4G to 8G and noticed no difference at all. Even when I had 2G due to a fautly ram chip, it wasn't all that different. The only advantage, is that I can store more on a ramdrive (ramfs). But of a waste of money in the end, but lesson learned.

64bit isn't a huge advantage. You end up having to install many 32 bit libraries anyway, due to 32 bit apps which you may run (ie, precompiled like doom3, or you cant recompile as 64bit). Those libraries take up additional disk space and RAM when loaded.

johnsfine 01-19-2013 06:39 AM

Quote:

Originally Posted by BoraxMan (Post 4873389)
I went from 4G to 8G and noticed no difference at all.
...
Those libraries take up additional disk space and RAM when loaded.

Odd mix of observations. You care about the several MB of extra ram use that you typically get in a 64-bit distro from needing some 32-bit shared libraries (redundant with 64 bit version of the same libraries also in ram). But you had such little need for ram that an upgrade from 4GB to 8GB didn't matter.

The extra disk space needed because of multi-lib is more than several MB, but it isn't one GB. The price difference between a disk drive of a several hundred GB vs. 1000 GB is typically less than 5 cents per incremental GB. So that is how I view the incremental disk space needed by 64-bit vs. 32-bit.

m1rr0rm3 01-21-2013 08:56 PM

Adding more ram
 
The main question should be do I use a 32-bit OS or a 64-bit OS?

Since the 32-bit OS' are being phased out slowly you should convert at a time that you can by building a computer that is capable of running a 64-bit OS.

I have 16 gb of ram on a RHEL v6.3 Workstation running the 64-bit kernel. I also use the same setup on my laptop but with 8GB of ram

- Chris


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