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-   -   8GB RAM, 64bit Linux? (http://www.linuxquestions.org/questions/linux-software-2/8gb-ram-64bit-linux-752203/)

MaGicMaX 09-02-2009 04:38 PM

8GB RAM, 64bit Linux?
 
Im looking to try 64bit linux on my desktop because i have a new computer with 8GB of RAM (i dont need it but i got it free so). I've only ever used Ubuntu, but im willing to try others. Which do u guys recommend? or do you think i should wait a while before trying 64bit? I may need to use 32bit programs still. Or better yet, is there a hack so i can utilize all my RAM in my current OS (Ubuntu Desktop 9.04 i386).

johnsfine 09-02-2009 04:42 PM

Quote:

Originally Posted by MaGicMaX (Post 3667326)
Im looking to try 64bit linux on my desktop because i have a new computer with 8GB of RAM (i dont need it but i got it free so). I've only ever used Ubuntu, but im willing to try others. Which do u guys recommend? or do you think i should wait a while before trying 64bit? I may need to use 32bit programs still. Or better yet, is there a hack so i can utilize all my RAM in my current OS (Ubuntu Desktop 9.04 i386).

I'm very happy with 64 bit Mepis. I also have a computer with 8GB of ram and I don't particularly need 8GB for anything I commonly run.

You can still run 32 bit programs easily on a 64 bit Linux. Installing them may be a little harder than installing the same on a 32 bit Linux, but not prohibitive. Also, you will find 64 bit versions of almost everything is available, so you might be wrong about even wanting to run any 32 bit programs.

You shouldn't need a "hack" to use all the ram with 32 bit Ubuntu (maybe depending on what you mean by "use"). You just need a PAE kernel.

I don't recall how Ubuntu names the various pre built kernels that are available to be installed through the package manager. If there isn't a pre built 32 bit build kernel that fits your needs, then at worst you need to build your own kernel.

I believe the option that turns on PAE support when configuring a kernel is HIGHMEM64G and I believe that Ubuntu has that in its 32 bit "server" kernel but not in 32 bit "desktop" kernels. IIUC, the server kernel has some scheduler differences that might make it unresponsive for some workloads on single core desktop systems. With a multi core CPU, it is much less likely that you would find a workload that would make the server version noticeably less responsive. You could try the server kernel and if you don't like it, build your own kernel.

With a 32 bit PAE kernel, each process is still limited to 3GB of ram. If you are running several big processes concurrently, then 32 bit PAE can make very good use of 8GB of ram. Even with just one significant process running, 32 bit PAE might make good use of additional ram for caching.

But if you want one process to use more than 3GB of ram, switch to 64 bit.

I think 64 bit is better. But the difference is usually small. You can switch from 32 bit to 32 bit PAE by replacing just the kernel. To switch to 64 bit you need to reinstall the whole distribution. I'm not sure I understand your situation: If this is a fresh install anyway, that eliminates the minor advantage of 32 bit PAE vs. 64 bit.

AlucardZero 09-02-2009 04:45 PM

64-bit is fine

MaGicMaX 09-02-2009 05:04 PM

Ok ill give 64bit a shot, but ive spent alot of time customizing my current setup, is there a way to upgrade to 64bit ubuntu without losing all this?

i92guboj 09-02-2009 05:08 PM

Quote:

Originally Posted by MaGicMaX (Post 3667354)
Ok ill give 64bit a shot, but ive spent alot of time customizing my current setup, is there a way to upgrade to 64bit ubuntu without losing all this?

If you are talking about user settings, you can just preserve your /home partition. If /home is not on a dedicated partition then you can just backup the contents of your home dir and then restore it. Make sure you backup the hidden files and dirs as well.

johnsfine 09-02-2009 05:11 PM

Quote:

Originally Posted by MaGicMaX (Post 3667354)
ive spent alot of time customizing my current setup, is there a way to upgrade to 64bit ubuntu without losing all this?

I don't think so. That is the advantage of 32 bit PAE over 64 bit for those that already have 32 bit installed.

Some advice if you do switch from 32 bit to 64 bit:
When I upgraded Mepis 7 to Mepis 8 (which upgrade also needed a full install) I installed into new partitions, preserving my old install of Mepis 7. That let me gradually find and copy things to get the new install customized similar to the old one, rather than require that I figure out in advance everything that I needed to extract or back up from the old install. If you have enough disk space, I suggest keeping the whole old install for a while after you start using the new one.

MaGicMaX 09-02-2009 07:38 PM

Quote:

Originally Posted by johnsfine (Post 3667362)
I don't think so. That is the advantage of 32 bit PAE over 64 bit for those that already have 32 bit installed.

Some advice if you do switch from 32 bit to 64 bit:
When I upgraded Mepis 7 to Mepis 8 (which upgrade also needed a full install) I installed into new partitions, preserving my old install of Mepis 7. That let me gradually find and copy things to get the new install customized similar to the old one, rather than require that I figure out in advance everything that I needed to extract or back up from the old install. If you have enough disk space, I suggest keeping the whole old install for a while after you start using the new one.

Ya i was just trying to write down everything i needed to change/backup. But since i have a 1TB drive, i think i could just do another partition, that way IF i find issues with 64bit i can always revert to my other setup. Thanks for the suggestion. Btw, i can always delete the old partition if im done with it right? then re-size my new one?

Edit: Besides being able to use more RAM (which i dont really think i need) is 64bit going to give more performance to a new 64bit compatible desktop computer?

nitrousoxide82 09-02-2009 07:54 PM

Quote:

Originally Posted by MaGicMaX (Post 3667469)
Besides being able to use more RAM (which i dont really think i need) is 64bit going to give more performance to a new 64bit compatible desktop computer?

It depends on the type of application. Image/video encoding/editing, games (for the CPU-dependent part) and such will get a nice boost, because x86-64 has more registers and can do 64-bit math faster.

"Simpler" apps will benefit, too, but not by much. But overall, I'd recommend run 64-bit even for machines with less than 4 GB of RAM (I have 2 GB on the laptop I'm using to type this, and I'm running 64-bit Arch Linux) and run whatever 32-bit applications you need using the compatibility libraries. I'd say full 32-bit OSes are only for the (now rare, I think) cases where the compatibility libs are no-go.

MaGicMaX 09-02-2009 08:25 PM

Quote:

Originally Posted by nitrousoxide82 (Post 3667483)
I'd say full 32-bit OSes are only for the (now rare, I think) cases where the compatibility libs are no-go.

About compatibility libs, are they automatically installed/used when installing 32bit packages using Synaptic Package Manager? Or would i have to manually do this to get my 32bit apps working? Also, if a package has both 32bit and 64bit versions available, will i be given an option in synaptic? I usually install my programs via synaptic, or .debs so...

nitrousoxide82 09-02-2009 08:58 PM

The basic 32-bit compatibility libs come in a package called ia32-libs. There are other 32-bit compatibility library packages, that may be needed by some specific application. And in general, Synaptic will offer options based on the current architecture you're running - so when running 64-bit it will, in general, offer you the 64-bit versions of the packages, and in case a program is 32-bit only the package for the 64-bit system will contain the same software but may be named differently or have a dependency on 32-bit library packages (which the APT system can resolve).

MaGicMaX 09-02-2009 09:28 PM

Ok great, i just have a few more concerns before i try it. Many say theres issues on 64bit with Flash(in firefox), Java, some Audio/Video codecs, Mplayer, and Wine (not a must for me but would be useful in some cases). Flash and Java support is a MUST have for me, as well as Mplayer and Audio/Video codecs, as i do alot of video and music encoding/decoding/editing. I also need Devede (DVD authoring suite using Mencoder) and SoundConvert (uses GStreamer codecs) to work. I also have a new video card (ATI 4870) and new motherboard (AMD 790X chipset), ive heard of drivers being behind for 64bit, specially with new hardware (which is my case). My CPU is AMD Phenom 2 X4 940. I want the best out of my system, but not if it means i cannot use the programs/codecs/plugins that i use on a daily basis, and certainly not if drivers are not fully functional and/or underdeveloped, or worse, unavailable.

johnsfine 09-02-2009 09:50 PM

Quote:

Originally Posted by MaGicMaX (Post 3667469)
i think i could just do another partition, that way IF i find issues with 64bit i can always revert to my other setup.

Good plan. I have both a / partition and a /home partition for each install (Mepis 7 that I haven't touched in a while and may delete soon and Mepis 8). I share a swap partition, since I don't use suspend to disk.

Quote:

Btw, i can always delete the old partition if im done with it right? then re-size my new one?
If you want the disk space, you could. Until I need the disk space of the old system, I'm consider those partitions to be waiting in case I suddenly decide to try another new distribution.

Quote:

Besides being able to use more RAM (which i dont really think i need) is 64bit going to give more performance to a new 64bit compatible desktop computer?
It depends on what applications you run and there isn't a lot of controlled comparison around to be sure of many differences. I know a lot of theory of which applications should be faster/slower when switching 32 bit to 64 bit, but I don't have a lot of real data to back it up.

Programs dominated by memory accesses tend to be slower in 64 bit because 64 bit has larger pointers and larger code both of which use cache space competing with other data and increase the number of memory accesses. You can find a lot of nonsense about wider data paths in 64 bit mode making memory access intensive programs faster. That is totally untrue. The important data paths are the same width in 32 and 64 bit mode and memory intensive programs are slower in 64 bit mode. I have tested the program that I work on professionally quite a lot doing such performance comparisons. It is significantly faster when compiled in 32 bit mode by the Intel (not GCC) compiler than when compiled in 64 bit mode by that same Intel compiler. But it is an unusual program (more memory and pointer intensive than most programs), plus the Intel compiler does much better than GCC with the register shortage of 32 bit mode. That same program runs a little faster as a 32 bit image under a 64 bit OS than it does under a 32 bit OS, so this 32 bit advantage is in the program image, not the OS.

Typical performance sensitive programs are more likely to have better performance compiled in 64 bit mode than 32 bit (especially using GCC instead of the non free Intel compiler). 64 bit mode has twice as many registers, which helps many programs (hard to predict which) and 64 bit mode uses SSE floating point by default instead of the old floating point instruction set, which helps a slightly more predictable set of programs.

Quote:

Originally Posted by MaGicMaX (Post 3667514)
About compatibility libs, are they automatically installed/used when installing 32bit packages using Synaptic Package Manager? Or would i have to manually do this to get my 32bit apps working? Also, if a package has both 32bit and 64bit versions available, will i be given an option in synaptic?

I may have missed something, but I've never seen any support like that in Synaptic. I have seen both those behaviors in Yum in Centos: If a package needs some 32 bit support, Yum figures that out and installs the right 32 bit package. If a package is available both 32 and 64, Yum defaults to 64 (on a 64 bit system) but can easily be told to install the 32 bit version or install both.

Synaptic (at least in Mepis) has a few packages of 32 bit libraries for use on 64 bit systems. Unlike the way it works with Centos/Yum, those are not the same packages as the 32 bit package of the same libraries for a 32 bit system. In my experience, when you want to install something that needs 32 bit libraries, the whole automatic dependency structure is effectively missing. You need to figure out for yourself which 32 bit package for 64 bit systems you need, then Synaptic can install it. Worse yet, some 32 bit libraries you may want are only available as 32 bit packages for 32 bit systems. Then, so far as I have figured out, Synaptic can't even install them. After you download the .deb file you must unpack it yourself and distribute the .so files to different directories than the .deb specifies. If you needed to do that a lot, I'm sure there would be a way to set up Synaptic to see the right directory aliases to make it all work automatically, but I've never seen instructions to set that up and you won't need to do it a lot. I never needed to do it at all. I installed 32 bit packages on 64 bit Mepis systems only out of curiosity about the process, never for lack of a 64 bit version.

Once a 32 bit package is installed, it runs smoothly/transparently on a 64 bit system. All the extra nonsense is just at install time.

Quote:

Originally Posted by MaGicMaX (Post 3667559)
Many say theres issues on 64bit with Flash(in firefox), Java, some Audio/Video codecs, Mplayer

I think I'm using all of those, all 64 bit, all installed the ordinary way and zero install or run time issues.

Quote:

and Wine
I use Wine on both 64 bit Centos and 64 bit Mepis. In both cases, I just selected the package and let it install normally and had no issues.

If I understand correctly, Wine supports only win32, not win64 even when running in 64 bit Linux. I use a win64 system at work, but mainly because of the ram limit and the file caching is so broken in win32. In Wine, I'm perfectly happy running win32 programs in a more stable OS, with better memory management and file caching than I can get with Windows. Even the compiler I use to compile win64 programs is actually a win32 program itself.

So when you read about Wine being 32 bit only, be careful about what that means. In any case, it does not mean Wine must run on a 32 bit Linux.

Quote:

Originally Posted by MaGicMaX (Post 3667559)
I also need Devede (DVD authoring suite using Mencoder) and SoundConvert (uses GStreamer codecs) to work. I also have a new video card (ATI 4870) and new motherboard (AMD 790X chipset), ive heard of drivers being behind for 64bit, specially with new hardware (which is my case). My CPU is AMD Phenom 2 X4 940. I want the best out of my system, but not if it means i cannot use the programs/codecs/plugins that i use on a daily basis, and certainly not if drivers are not fully functional and/or underdeveloped, or worse, unavailable.

Virtually anything open source is available 64 bit. When first recompiled as 64 bit, there will be bugs, because programmers got sloppy and made assumptions about the relative sizes of data types (especially ints vs. pointers) that won't be true in x86_64. But
1) Quite a lot of open source is the same across many other platforms even less similar to 32 bit x86, so those programs have had such bugs flushed out long ago.
2) x86_64 has been popular for a while, so the serious bugs were found long ago. In Centos 5.3 I've seen a few minor bugs still left from the long ago 32 to 64 bit port (something displaying wrong even though it works right). In Mepis 8, I haven't noticed any.

MaGicMaX 09-02-2009 10:36 PM

Thanks for the info johnsfine,

Looks like the only issue i might have will come when/if i need to install a 32bit only application, which hopefully wont happen. I guess the only way to know if 64bit is right for me is to just try it out. I guess like you said, i could always use the "old" partition for another distro, im sure ill want to experiment at one point. Just curious, how does Mepis differ from Ubuntu, sounds like its also Debian based.

Edit: Does Mepis update itself like Ubuntu does with "Update Manager"?
Edit2: Does it have multiple workspaces like ubuntu?

johnsfine 09-03-2009 07:42 AM

Quote:

Originally Posted by MaGicMaX (Post 3667617)
how does Mepis differ from Ubuntu

Not very much, except that Mepis defaults to KDE and Ubuntu defaults to Gnome and KDE vs. Gnome are pretty different (but "default does not mean "stuck with").

Mepis has a few "Mepis assistant" programs that simplify a few of the trickier aspects of system configuration.

Mepis defaults to permitting root GUI login, while Ubuntu tries to make the method of enabling that secret. I think it is better enabled. A really stupid beginner can get into more trouble with root enabled, but I prefer "beginner friendly" to target beginners lacking just knowledge, not intelligence. Its a lot easier for such a user to use many of the same GUI tools the same way when root as when logged in normally. Even a beginner can understand not to surf the net or try programs from untrusted sources when logged in as root. When I want to do a lot as root, but also surf the net, I use the ctrl-alt-F7, ctrl-alt-F8 mechanism to switch between GUI sessions logged in as me and logged in as root.

Quote:

Edit: Does Mepis update itself like Ubuntu does with "Update Manager"?
I don't know the names of the programs other than apt and synaptic involved in update. What part does Update Manager do? Something runs automatically and notices updates are available. It shows that on the task bar. When clicked, it brings you to Synaptic so you can install updates. Minor updates are frequent and easy. The update from Mepis 7 to Mepis 8 took a reinstall.

Quote:

Does it have multiple workspaces like ubuntu?
I haven't noticed that term (workspaces) anywhere.

i92guboj 09-03-2009 07:53 AM

If by workspaces he means different desktop areas with different windows on them (pages, desktop, workspaces, or whatever each wm/de wants to name them), most actual desktkops and wms do support them. Both kde and gnome support that feature.


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