Virtual memory

[Javier Ortiz Guajardo]

A student question.

Where is the virtual memory located? on physycal memory? or is always working in Device swap?

can somebody explains me?

Thanks.

[Hai Nguyen_1 · Accepted solution]

Javier,

By default, the virtual memory are in two locations: RAM (controled by Kernel parameter swapmem_on) and one primary swap device (/dev/vg00/lvol2). You can configure additional swap DEVICE or swap FILE SYSTEM. For more info, "man 1m swapon" without quotes.

Hai

[A. Clay Stephenson]

It's both and still more - you might be using filesystem swap.

The concept behind virtual memory is that a process doesn't care. It simply makes a request to read or write to an address - always a virtual address. This virtual address is then translated to an actual physical address and it might require that memory pages be brought in from swap in order to access it. Ultimately, the process must access the data in physical RAM.

Finally, in the HP-UX world there is pseudoswap that doesn't exist anywhere. It's simply a kernel bookeeping mechanism that allows physical memory to exceed swap space and still allow more processes than physical swap space would normally allow to run.

[Paddy_1]

May be this will help you understand completely about it
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The Paging Game
by Jeff Berryman, University of British Columbia, 1972
The Paging Game was written by Jeff Berryman when he was working on project MAC, specifically one of the virtual memory systems. The version best known to IBM and MVS sites from the mid-1970s onwards is first, followed by the original:
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Here is a link to it
http://www.isham-research.com/zarking.html

[Uday_S_Ankolekar]

There is a very good doc avalaible in /usr/share/doc/mem-mgt.txt

This will give you how is memory has been handled

-USA..

[Uday_S_Ankolekar]

There is a very good doc avalaible in /usr/share/doc/mem-mgt.txt

This will give you how memory has been handled

-USA..