# 6gb memory in i686?

## koschi

Hello, 

got a question. Conky shows me 6gb of ram but my system is still 32bit. So is it just shown or can the system really access it? 

http://img812.imageshack.us/img812/7462/bildschirmfoto1k.png

And why is no swap space used? 

I got a core i5 processor. 

THX!

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## disi

It's called PAE support: http://en.wikipedia.org/wiki/Physical_Address_Extension

So you can use up to 64GB on a 32bit system, but each single application not more than 4GB.

Here is some information about swappiness:

http://kerneltrap.org/node/3000

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## kernelOfTruth

yeah that works,

only make sure you have PAE enabled

I once used 32bit with 8 GiB of RAM and it worked fine

there seems to be some significant difference in caching behavior between 32bit vs. 64bit for the bad:

 ReiserFS bugs, 32-bit vs 64-bit kernels, cache vs inode memory 

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## chithanh

On Linux the practical limit for PAE (CONFIG_HIGHMEM_64G) is 16 GB because you will run out of lowmem. And individual processes are still limited to 32 bit address space.

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## augury

I have a two processor xeon board that is running at 32-bits.  It has 8gb (2X4gb) of frame-buffered ecc memory.  The pci bus is still the 64bit server type.  I never migrated to x86-64.  But my pcie is 8x with an adaptor.   :Crying or Very sad:   Shameful.

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## The Doctor

since the i5 is a 64-bit processor, you will really see big improvement by reinstalling as a 64-bit.

PAE is not a good way to get to you extra 2 gigs.

see  Linus Torvalds' take.

with 64 bit, you will also get a performance boost in video and intensive floating point calculations. Well worth it in my opinion.

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## The Doctor

My favoret line:

 *Quote:*   

> 
> 
> So repeat after me: PAE didn’t ever really fix anything. It was a mistake. It was just a total failure, and the result of hw engineers not understanding software.
> 
> 

 

 *disi wrote:*   

> 
> 
> So you can use up to 64GB on a 32bit system, but each single application not more than 4GB
> 
> 

 

yes, AND

 *Linus Torvalds wrote:*   

> Yes, Linux supported it, and probably did so better than anybody else. But “better than anybody else” still wasn’t very good. Because you couldn’t use normal pointers to point to arbitrary physical memory, all the memory that couldn’t be accessed directly (ie anythign that didn’t fit in the virtual address map, which also had the user space memory in it) was basically limited to “special uses only”.
> 
> 

 

and more calculations == longer time.

Memory access should be a constant time operation, not big O of of n cubed or something.

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## koschi

Hi guys, 

thank you all for the answers. I thought about migrating to 64bit. My Gentoo recently moved to its 3rd laptop without any problems. Due to the fact that migrating to 64bit means a complete new installation I don't want to do this step - too risky to loose my well running system... it's almost 7 years old. 

Currently I don't need the 6gb of ram for my daily tasks. Maybe later. It was a free aditional feature when I bought the laptop. 

Closing this thread now. THX!

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## s_bernstein

I migrated last year from an old 32-bit gentoo. Was easier than I thought and took less than a day. There are some shortcuts you can use, if you have an already running system. Basicly what I did was a fresh base installateion in 64-bit according to the handbook. Then I copied my world file and my /home and /etc, started an emerge -auvDN world and off you go.

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## koschi

 *s_bernstein wrote:*   

> I migrated last year from an old 32-bit gentoo. Was easier than I thought and took less than a day. There are some shortcuts you can use, if you have an already running system. Basicly what I did was a fresh base installateion in 64-bit according to the handbook. Then I copied my world file and my /home and /etc, started an emerge -auvDN world and off you go.

 

Mmh, that sounds easy... I will make a backup and give it a try.

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## NeddySeagoon

koschi,

Pick and choose what you reuse from /etc  you cannot use it all.

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## koschi

 *NeddySeagoon wrote:*   

> koschi,
> 
> Pick and choose what you reuse from /etc  you cannot use it all.

 

I noticed that yesterday... Fortunately I had a backup  :Wink: 

I will prepare that more accurate and give it another try later. GCC was messed up and the whole profile stuff. 

Will try to find a proper HowTo. I don't want to loose my configuration and user information.

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