Virtual vs Paging, hopefully a new question

[Guest]

I posted a question before about how windows handles the 3GB switch, and got
some really great responces. I now have a new question allong the same lines.

How Does Windows split the processing of an application between physical and
virtual memory?

I am trying to build my understanding of this issue as it is becoming more
promenent in the 3D CAD industry.

So just to be more clear, i understand that windows uses both physical
memory and virtual memory to run an application, but how much of each?

thanks for your help!

-jeff

 

[Guest]

here is some data
for your memory
bank:

http://en.wikipedia.org/wiki/Virtual_memory

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..

 

[John John]

I posted a question before about how windows handles the 3GB switch, and got
some really great responces. I now have a new question allong the same lines.

How Does Windows split the processing of an application between physical and
virtual memory?

I am trying to build my understanding of this issue as it is becoming more
promenent in the 3D CAD industry.

So just to be more clear, i understand that windows uses both physical
memory and virtual memory to run an application, but how much of each?

thanks for your help!

-jeff

It doesn't split it between RAM and virtual memory, it uses a form of
"demand paging". The processor can only access data that is stored in
the RAM, no processing can be done directly with the data that is stored
in the pagefile. When an application is started it makes a request for
memory and the Memory Manager gives or allots to the process a minimum
and maximum amount of memory, this is called the "Working Set", all
running processes have a working set. If the application makes
increased demands for additional memory the Memory Manager will "expand"
the working set, to do so the Memory Manager will "trim" the working
sets of other non active applications, it will take memory pages from
other applications, move the contents of those memory pages to the
pagefile and zero out the pages then make them available to the
application making demands for additional RAM.

That, in a nutshell, is how it happens. Of course underneath it all
it's a lot more complicated than that. The working sets are constantly
monitored and are adjusted once every second. The memory pages are
moved out of working sets in an orderly fashion, to minimize paging the
Memory Manager will take pages from the zeroed page list or from the
free list. The article below explains how the applications can use more
memory than the actually installed RAM.

How Windows NT Provides 4 Gigabytes of Memory
http://support.microsoft.com/kb/99707

 

[Guest]

Thank you John John, that was a really helpful way to explane things, thats
exactly what i was looking for.

 

[John John]

You're welcome.

John

Thank you John John, that was a really helpful way to explane things, thats
exactly what i was looking for.

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