Ideal Swap Partition Size

Aaron Konstam akonstam at sbcglobal.net
Fri Jan 23 20:47:50 UTC 2009


On Fri, 2009-01-23 at 11:34 -0430, Patrick O'Callaghan wrote:
> On Fri, 2009-01-23 at 08:53 -0600, Aaron Konstam wrote:
> >  All this avoids the question I asked. VM processing involves paging
> > between a memory space and an address space. The question is where is
> > the address space of the process? It can't be the computer's real
> > memory because that would be the memory space. 
> 
> Now you're confusing me. What do you mean by "memory space" and "address
> space"? Paging involves (among many pther things) moving data between
> main memory and a backing store. The data belongs to the "address space"
> of a process, or possibly several processes in the case of shared pages.
> "Address space" is a logical concept meaning the range of addressable
> memory locations in the process virtual memory. I've no idea what you
> mean by "memory space" unless it's the physical main memory.
> oo
> poc
> 
The  whole philosophy of virtual memory is based on the idea that you
want to run your programs in an environment that has more memory than
the real memory of the machine. So you  operate in a large memory called
the address space. This address space is broken up into pages as is real
memory.. When a page is accessed by the cpu that page of memory may be
in the real memory (as noted in page tables) or not.
If not the page is moved into real memory  and processed. Eventually the
real memory will be full so pages no longer needed will be placed back
in the address space. It is this process that is most properly called
Virtual Memory.

This is explained in nearly all textbooks on Computer Architecture. So
the question remains, where is the address space in Linux.
--
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"... the Mayo Clinic, named after its founder, Dr. Ted Clinic ..." --
Dave Barry
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Aaron Konstam telephone: (210) 656-0355 e-mail: akonstam at sbcglobal.net




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