x64 not showing all 4GB

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x64 not showing all 4GB

Postby Iterator on Thu Jun 25, 2009 12:34 am

I just installed the x64 edition and for some reason the System Monitor does not show 4GB of RAM.

I checked all the SODIMMs just in case, its 4GB total.
As in the screenshots below, System Monitor does not show all 4GB
Firefox says I am running the 64-bit build.

I have an Intel Core 2 Duo T5750.
My video card is Ati Xpress 1250. There is no setting in the BIOS about how much memory it can allocate.

So anyone have any ideas what is going on here?

Screenshot-System Monitor.png
Screenshot-System Monitor.png (43.41 KiB) Viewed 3822 times

Screenshot-About Mozilla Firefox.png
Screenshot-About Mozilla Firefox.png (65.55 KiB) Viewed 3822 times
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Re: x64 not showing all 4GB

Postby emorrp1 on Thu Jun 25, 2009 4:22 am

read this for a full, easy-to-read explanation: http://www.dansdata.com/askdan00015.htm
However there may be something more here, as I was under the impression that Linux did the re-allocate above method.
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Re: x64 not showing all 4GB

Postby DrHu on Thu Jun 25, 2009 7:09 am

http://www.cyberciti.biz/faq/ubuntu-lin ... -solution/
Option # 1: Use 64 bit Ubuntu Linux

64 bit Linux kernel will take care of 4G or more memory. Just grab latest 64 bit version and install it.
Option #2: Install PAE enabled kernel

Open terminal and type the following command:
$ sudo apt-get update
$ sudo sudo apt-get install linux-headers-server linux-image-server linux-server


Mint..pae??
viewtopic.php?f=49&t=22706
viewtopic.php?f=49&t=27775
http://forums.whirlpool.net.au/forum-re ... 52911.html
4) PAE itself (the technology that enables a 32-bit OS to address up to 64 GB of RAM), slows down memory addressing and memory referencing. That is why PAE is disabled by default on my kernels.

Summary: It is not best to use the Ubuntu Server kernel on desktop systems. Sure, it works, but not optimally. If you want to use the a 32-bit Ubuntu, you are much better off recompiling your own kernel with PAE enabled, than to use the Ubuntu Server kernel.

Of course, considering that using the AMD64 port will also give you about 10%-15% speed boost, you are missing on a lot of performance by using the 32-bit Ubuntu Server kernel on a 64-bit capable CPU.

posted by aryonoco (#225791)
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Re: x64 not showing all 4GB

Postby Iterator on Thu Jun 25, 2009 8:05 am

So what you are saying is that even though I did install the 64-bit edition of mint, it still won't be able to see all 4GB since it does not have a 64-bit kernel?
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Re: x64 not showing all 4GB

Postby richyrich on Thu Jun 25, 2009 8:09 am

Hi Iterator,
No, I think DrHu didn't read your post, or is trying to confuse you. How much shared vga memory do you have allocated?

regards, Richard

ps: If you read the second half of the link emorrp1 gave you (below the Windows memory pic), there is a much better explanation.

EDIT: spelling! :oops:
Last edited by richyrich on Thu Jun 25, 2009 9:09 am, edited 1 time in total.
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Re: x64 not showing all 4GB

Postby Iterator on Thu Jun 25, 2009 8:17 am

I'm not really sure, there is no option in the BIOS to select this, I don't believe its almost 1GB allocated for vga though.
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Re: x64 not showing all 4GB

Postby richyrich on Thu Jun 25, 2009 8:19 am

You may want to check your Manufacturers website, I've seen some that take up anywhere from 64Mb to 1.5Gb of reserved space!
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Re: x64 not showing all 4GB

Postby Iterator on Thu Jun 25, 2009 8:45 am

UMA Frame Buffer size: Vista Logo Basic

Vista Logo Basic requires 512MB of ram
Vista Logo Premium requires more than 512MB of ram

I can switch between Basic and Premium settings, I believe this will tell the card to use more RAM.
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Re: x64 not showing all 4GB

Postby Iterator on Thu Jun 25, 2009 7:50 pm

Turns out there were more options for UMA size in the BIOS. I selected "XP Recommended" nothing changed. I then set it to "128MB" then now in System Monitor it now shows that I have 3.2GB. I'm still trying to figure out where the other 0.8GB went.

Anyone have any ideas where it could have gone?
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Re: x64 not showing all 4GB

Postby Fred on Thu Jun 25, 2009 9:04 pm

Iterator,

If in fact you did install the 64 bit system, your kernel should be correct. You didn't change it did you? So that is probably not the issue.

I would suggest you check your motherboard against the manufacturers specifications to determine if it will operate in 64 bit mode. Believe it or not, a lot of the first so-called 64 bit motherboards would run 64 bit CPUs and OSs, but only in 32 bit mode.

I know, it sounds unreasonable, but it is true none-the-less. :-)

If this is the case, then you are getting the memory availability that I would expect. In a 32 bit system, up to 1 Gig of the 4 Gig address space is reserved for hardware and other system purposes.

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Re: x64 not showing all 4GB

Postby Iterator on Thu Jun 25, 2009 9:37 pm

I am certain it is correct. I even ran the live CD on a Pentium M, says system not 64-bit. So I am sure I got the right ISO.

I don't think LG releases any information about what motherboard is used in their system. and I am certain that if I ask them why can't my OS see all 4GB they will say either:

1) 32-bit operating systems can only use up to 3GB
2) We do not support any operating systems other than what was preinstalled on your machine.

---

I am really certain that I am using a 64-bit kernel. Firefox says it is using a 64-bit build. Songbird is using a 64-bit extension.

I ran some commands, got this:
Code: Select all
jon@LG-laptop ~ $ free -m
             total       used       free     shared    buffers     cached
Mem:          3292       1129       2163          0         28        554
-/+ buffers/cache:        546       2746
Swap:         9648          0       9648
jon@LG-laptop ~ $ uname -r
2.6.28-11-generic
jon@LG-laptop ~ $


I find it a little odd that I cannot find a reference to "64-bit" or "x86-64" anywhere, like in System Monitor.
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Re: x64 not showing all 4GB

Postby subslug on Thu Jun 25, 2009 11:58 pm

I guess this doesn't really prove anything but I have 4Gb of ram on my 64 bit install and it's showing 3.8Gb


Image
I don't really know why yours is reading so much less? My system does have built in video but, I'm not using it and instead have an add on card.
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Re: x64 not showing all 4GB

Postby Fred on Fri Jun 26, 2009 12:17 am

subslug,

In your case, it wouldn't surprise me if some of your RAM is being reserved for your on-board video, even though you aren't using it. If I were you I would look closely at your BIOS settings for a way to disable possible video caching.

In Iterator's case I suspect his hardware isn't capable of running in 64 bit mode and is automatically falling back to 32 bit addressing.

Fred
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Re: x64 not showing all 4GB

Postby Iterator on Fri Jun 26, 2009 10:48 am

Fred wrote:subslug,

In your case, it wouldn't surprise me if some of your RAM is being reserved for your on-board video, even though you aren't using it. If I were you I would look closely at your BIOS settings for a way to disable possible video caching.

In Iterator's case I suspect his hardware isn't capable of running in 64 bit mode and is automatically falling back to 32 bit addressing.

Fred


What could prevent the hardware from running in 64-bit mode?
I also looked at the boot options screen (recovery mode, memory test, etc) each selection shows x64 so 64-bit kernel is definitely installed.
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