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maurizioOffline
Post subject: ram usage not sure  PostPosted: 09.12.2012, 20:03



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Hallo,

I'm running Aptosid on a Compaq netbook, AMD processor, 4 GiB ram.
This I encountered not only on my notebook, but in every other pc in which I installed Debian or its derivates.
Running Top it always shows much more ram usage than running System Monitor.
Here is a screenshot, but I suppose you can see in your own pc also.
In my pc Top is showing 3,1 GiB ram used, while System Monitor just 0,6 GiB!
Running Htop gives ram consumption similar to System Monitor.
Do I make mistakes in reading?
Or if I don't do mistakes, to which application sould I believe?

Also, both applications give only 3,5 GiB total, while Iread that Debian i386 can manage up to 7 Gib total ram.

Thank you for your answers!



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slhOffline
Post subject: RE: ram usage not sure  PostPosted: 10.12.2012, 00:14



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Determining RAM usage on Linux is pretty difficult, do you count only the RAM needed by your application or also all the RAM taken by the libraries needed by your application… Up to this point, the world is still 'easy', but many applications share a couple of the same libraries (qt4, gtk2, etc.) - which means if two applications need the same functionality of a library, their RAM usage can be shared among both applications as well (to quite some extent, at least), with KSM this can even span virtual machines…

As you see, this quickly becomes pretty complex with loose boundaries, even before we come to distinguishing between physical- and virtual memory requirements.
 
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maurizioOffline
Post subject: RE: ram usage not sure  PostPosted: 10.12.2012, 13:31



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so how can I know how many ram is left free for other applications I want to run?
 
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muchan
Post subject: RE: ram usage not sure  PostPosted: 10.12.2012, 22:14
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Maybe with command "free" or "free -h"?
Look the column under "free" in the line of "-/+ buffers/cache:".
 
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DonKultOffline
Post subject: RE: ram usage not sure  PostPosted: 11.12.2012, 09:54
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My preferred website to answer this and similar questions: http://www.linuxatemyram.com/

Regarding more than 4 GB RAM and i386: I think Debian activated PAE "recently" in their kernels, but this comes with performance penalties. Our take (and their take very soon as this was only a temporary thing) is: If you want to use that much RAM install amd64 instead – especially now that MultiArch has landed (alternatively you can install an amd64 kernel even if the rest of your system is i386, it is just a bit more work for no benefit as you could just as well profit from a complete amd64 userspace instead).

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maurizioOffline
Post subject: RE: ram usage not sure  PostPosted: 11.12.2012, 17:56



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yes, it's exaustive, now I know how to read ram consumption in linux!
Running "free -m" it gives 3,2 GiB free ram. Feel more comfortable!
I won't be frightened anymore by cached ram.
About 64bit systems, I tried it, but since I'm working with CAD drawing systems, many of these software are only for 32bit, so I had to switch to this. Looking forward for future development!
 
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DonKultOffline
Post subject: Re: RE: ram usage not sure  PostPosted: 11.12.2012, 19:35
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      maurizio wrote:
About 64bit systems, I tried it, but since I'm working with CAD drawing systems, many of these software are only for 32bit, so I had to switch to this. Looking forward for future development!

Feel free to try it out in a virtual machine, it might work better than you think. I have posted a thread in the dragons forum here about how to activate MultiArch – after that you should be able to install the 32bit applications just like you would if it would be a i386 system.

MultiArch is currently a work in progress - works for me and many others, but it depends a bit on the specific software involved (or to be specific on the packages/libraries these applications depend on). Hence try it out in a VM, if it works you plan how you move to a 'real' amd64 system – if not you have at least tried, you might be able to give feedback (aka write bugreports) and you can periodically retry until it works.

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maurizioOffline
Post subject: RE: Re: RE: ram usage not sure  PostPosted: 12.12.2012, 19:35



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Thanks I'll surely try it.
 
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