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Old 08-15-2011, 09:01 AM   #16
johnsfine
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Quote:
Originally Posted by unkn(0)wn View Post
Let me tell you , when i play games in windows my ram usage reaches to 3.2 GB in task manager , so windows can't be lying !
How do you know Windows isn't "lying" about that 3.2GB? Or maybe you're misunderstanding the meaning of that 3.2GB stat. Probably, you're also misunderstanding the meaning of the 2.3GB Linux stat you started with.

Of your 4GB physical ram.
1) Part of it is unusable by any OS regardless of what you do.
2) Part of it is usable by a 32 bit PAE Linux or by 64-bit Windows or Linux, and is not usable by 32-bit Windows nor non PAE 32-bit Linux.
3) Part of it is reserved for use by your Intel(R) HD graphics.
3a) Windows (actually NVidia software in Windows) might be able to do things that Linux can't to make part or all of the ram reserved for Intel graphics available for other purposes when the Intel graphics aren't using that ram. That is the only way 32-bit Windows might have more ram usable than Linux on your laptop.

There is a table of physical memory info that the BIOS provides to the OS at startup. You should be able to get it with the command:
dmesg | grep e820

If you post that table to this thread, any expert here can tell you the amount of ram in (2) in my list of possibilities above and the total of (1) and (3) and maybe some estimate of the split between (1) and (3).

That should give you more perspective on the problem and potential for improvement.

For installing the PAE kernel, Ubuntu has a GUI package manager. (I haven't kept track of which GUI package manager is in which version of Ubuntu. Personally, I'm only experienced with the Synaptic GUI package manager, which is in some versions of Ubuntu).

With Synaptic, it is very easy to search for something like PAE to find all available packages with PAE in their name. Then it should be obvious which of those packages is the current (for your version of Ubuntu) PAE kernel. Then it is trivial to select it and install it.

Unlike most package installs, a kernel package install does not take effect until the next reboot.

Last edited by johnsfine; 08-15-2011 at 09:15 AM.
 
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Old 09-03-2011, 11:58 AM   #17
Luke_Wolf
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Um.. You people do realize that if that's the OEM install of Windows 7 that it is going to be 64 bit version, right?... right? There's no reason that they'd install the 32 bit version on an i5 unless the OEM is incredibly stupid, particularly paired up with 4GB of RAM. So no, Windows is not lying, he's simply running the 64-bit version.

OP: The solution to your problem is either to install a PAE kernel which allows up to 64 GB of RAM, or use a 64-bit version of the distro. If memory serves though Ubuntu doesn't have a 64-bit version, although other alternatives such as Fedora or openSUSE do have such.
 
Old 09-04-2011, 07:25 PM   #18
godh8sme
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I am using a 64 bit version of Ubuntu 11.04 on a system with 16 Gig of RAM that it fully utilizes. However, there is no way to just upgrade from the 32 bit to the 64 bit version. You will need to do a re-install.
 
Old 09-29-2011, 12:08 PM   #19
Akflash
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How bout Mandriva 2011 64 bit? Have loaded my first Mandrake 7.2!
 
Old 10-02-2011, 01:01 AM   #20
parag_dhake
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what is swap?

hallo dude

swap is internal partition of Linux if you not create it.
You can also make swap partition at the time of OS installation.
Usually swap is made 2*ram but it not mandatory.
In simple language when your start some program & in your ram there is some program but in sleep mode then these program is transfer in swap partition (without informing that program)
Hence your new program get chance in ram.
My suggestion is always made swap partition double of ram it increase the speed of your system

Last edited by parag_dhake; 10-02-2011 at 01:05 AM.
 
Old 10-04-2011, 03:10 AM   #21
16pide
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No, making swap space be twice the size of RAM is not always a good idea.
For example, my laptop has 12 GB of RAM. I never used more than 8GB of it.
It does not have any swap space. It runs blazing fast.
I could add some swap space, say 4GB, and then my virtual memory would be 16GB, but like I said I never needed more than 8GB...

Now regarding speed. Adding swap space has never increased speed and never will.
Remember, swap space is on disk. When it is used, the system swaps information in ram with information on disk. this can never be faster than running from RAM without swapping.
You can add as many GB of swap you want, it will never make your system faster.
 
Old 10-04-2011, 07:44 AM   #22
johnsfine
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Quote:
Originally Posted by 16pide View Post
I could add some swap space, say 4GB, and then my virtual memory would be 16GB,
That concept of "virtual memory" as the sum of physical memory plus swap is completely unsound. It is based on a serious misconception of virtual memory and it leads to further misunderstandings.

Quote:
I never needed more than 8GB...
"Needed" is ambiguous in a few ways in that sentence.

Quote:
Adding swap space has never increased speed and never will.
Nonsense. There are moderately common cases in which adding swap significantly increases speed. On a lightly loaded workstation with 12GB of ram it is pretty hard to describe a possible speed increase from adding swap, and such a speed increase would be very tiny even if it occurred. But in other configurations a big speed increase is possible.

Quote:
When it is used, the system swaps information in ram with information on disk.
Regardless of whether you have any swap space, Linux still swaps information in ram with information on disk. Most significantly, it brings in pages from exectuables, .so files and other mapped files, usually displacing other such pages. Swap space allows Linux to displace anonymous pages when they are much less recently accessed than other pages. The theory of virtual memory is based on the idea that less recently accessed pages are also less likely to be accessed again in the future. So forcing Linux to displace a recently accessed non anonymous page instead of a non recently accessed anonymous page likely increases total disk I/O and slows the system throughput.

If your 12GB system hasn't even filled up ram with cache, then it wouldn't use any swap space even if it had any. Even if ram is full (including cache) it won't want to use swap space unless some anonymous page is significantly less recently used than any non anonymous page in cache. But if it does want to use swap space then having some swap space would probably make the system a tiny bit faster.

For a moderately heavily used 4GB system, swap space may significantly improve system throughput. With a heavier workload relative to ram size, swap doesn't just improve speed, it is necessary to avoid failures due to lack of memory.

Quote:
No, making swap space be twice the size of RAM is not always a good idea.
I agree. 2 times ram was always a stupid rule and has gotten stupider. My advice for a workstation is to make swap space about 2GB larger than the amount of swap you reasonably expect the system to use. For a lightly loaded workstation, reasonable use of swap space is very small, so 2GB more than that is 2GB. If there are specific reasons real swap use would be expected than add that expected use to 2GB. But if your system is seriously short of disk space, either buy a real disk or be less generous in allocating swap space.

Last edited by johnsfine; 10-04-2011 at 07:53 AM.
 
Old 10-05-2011, 03:27 AM   #23
16pide
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Quote:
That concept of "virtual memory" as the sum of physical memory plus swap is completely unsound. It is based on a serious misconception of virtual memory and it leads to further misunderstandings.
Can you explain this please?
I read again http://en.wikipedia.org/wiki/Virtual_memory and the graph in top-right and don't see where you think I misunderstand something
 
Old 10-05-2011, 07:50 AM   #24
johnsfine
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Quote:
Originally Posted by 16pide View Post
I read again http://en.wikipedia.org/wiki/Virtual_memory and the graph in top-right and don't see where you think I misunderstand something
Minor issue: The picture in the top right of that is a simplification leaving out quite a lot of important possibilities.

Major issue: That picture says Disk not Swap space for non resident sections virtual memory. That is an important distinction.

Only anonymous memory goes into swap space when it is non resident. Linux processes typically have a significant amount of non anonymous memory that is non resident, meaning it is on disk, but not in the swap space.

Having zero or too little swap space limits the amount of anonymous memory that can be non resident, so average access to anonymous memory is faster. But in doing so it reduces the amount of non anonymous memory that can be resident and makes access to non anonymous memory slower.

But remember, I'm not talking about the situation on a workstation with 12GB of ram and a low ram workload.

Last edited by johnsfine; 10-05-2011 at 07:52 AM.
 
  


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