Hello, AFAIK, in windows 7, **32 bit**, there is a limit of 3GB physical RAM which can be recognized by the operating system. This means that if you have 4GB of RAM, only 3 will be used. My question is: 1) In Fedora 12 32 bit default installation , does the kernel knows more than 3 GB of RAM ? what is the limit ? 2) In Fedora 12 64 bit default installation , does the kernel knows more than 3 GB of RAM ? what is the limit ?
Rgs, Mark
On 12/17/2009 12:51 PM, Mark Ryden wrote:
Hello, AFAIK, in windows 7, **32 bit**, there is a limit of 3GB physical RAM which can be recognized by the operating system. This means that if you have 4GB of RAM, only 3 will be used.
This is usually a BIOS limitation.
My question is:
- In Fedora 12 32 bit default installation , does the kernel knows
more than 3 GB of RAM ? what is the limit ?
The same. It uses what the BIOS tell it is available, unless you run a PAE kernel. The Physical Address Extensions allow you to address the full amount of your RAM.
- In Fedora 12 64 bit default installation , does the kernel knows
more than 3 GB of RAM ? what is the limit ?
64-bit does not have the artificial limitation (the actual limit is *much* higher than you can currently put in a machine today) that 32-bit does. You should see the same with Windows too.
Rgs, Mark
Kevin J. Cummings wrote:
On 12/17/2009 12:51 PM, Mark Ryden wrote:
My question is:
- In Fedora 12 32 bit default installation , does the kernel knows
more than 3 GB of RAM ? what is the limit ?
The same. It uses what the BIOS tell it is available, unless you run a PAE kernel. The Physical Address Extensions allow you to address the full amount of your RAM.
And the PAE kernel will be installed by default. So the 32 bit Fedora could be considered without limit too.
Once upon a time, Roberto Ragusa mail@robertoragusa.it said:
And the PAE kernel will be installed by default. So the 32 bit Fedora could be considered without limit too.
IIRC, the practical limit with PAE is something like 8G or 16G RAM. With more, you end up using all the low RAM for page tables and can't get any actual work done.
2009/12/18 Roberto Ragusa mail@robertoragusa.it:
Kevin J. Cummings wrote:
On 12/17/2009 12:51 PM, Mark Ryden wrote:
<--SNIP-->
And the PAE kernel will be installed by default. So the 32 bit Fedora could be considered without limit too.
-- Roberto Ragusa mail at robertoragusa.it
By the way, will I see any speed burst if I replace PAE kernel with the ordinary one (not PAE) on 32-bit F-11? My computer has only 2 GB of RAM.
Hiisi wrote:
2009/12/18 Roberto Ragusa mail@robertoragusa.it:
Kevin J. Cummings wrote:
On 12/17/2009 12:51 PM, Mark Ryden wrote:
<--SNIP-->
And the PAE kernel will be installed by default. So the 32 bit Fedora could be considered without limit too.
By the way, will I see any speed burst if I replace PAE kernel with the ordinary one (not PAE) on 32-bit F-11? My computer has only 2 GB of RAM.
The non-PAE version used to be preferred. But experts say the performance impact with PAE is minor (at the "almost unmeasurable" level) with recent versions. There is also some small security advantage with PAE (NX protection, IIRC).
Roberto Ragusa wrote:
Kevin J. Cummings wrote:
On 12/17/2009 12:51 PM, Mark Ryden wrote:
My question is:
- In Fedora 12 32 bit default installation , does the kernel knows
more than 3 GB of RAM ? what is the limit ?
The same. It uses what the BIOS tell it is available, unless you run a PAE kernel. The Physical Address Extensions allow you to address the full amount of your RAM.
And the PAE kernel will be installed by default. So the 32 bit Fedora could be considered without limit too.
IIRC 36 bits, or 64GB, reasonable design for a number chosen decades ago. Still a reasonable size for anything but servers, most motherboards support 16-24GB max, and only half of that if you use affordable 2GB memory instead of 4GB.
The PAE kernel allows use of the NX bit, to prevent execution of non-program memory areas.
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Bill Davidsen -
Chris Adams -
Hiisi -
Kevin Cummings -
Mark Ryden -
Roberto Ragusa