My software vendor tech support is telling me virtual memory = total system memory.

[spidey07]

Originally posted by: cjchaps
At work I help support a really expensive reporting software package. If I don't know the answer, we can call up the software vendors because we pay for their support. We are having issues dealing with memory, and here is a quote from one of the emails they sent me on this subject:

Virtual Memory is the total amount of memory on a machine (it includes the physical Memory RAM as well as the Page File).

Oh well, don't you just love tech support.

ummm, that is correct.

virtual memory = physcial ram plus page file

 

[spidey07]

Originally posted by: pulse8

Originally posted by: Argo

Originally posted by: pulse8

Originally posted by: Argo

Originally posted by: pulse8

Originally posted by: Argo
Technically he's right, he just could've put it better. Virtual memory is total memory available to your programs, it's the total of physical memory and your page file.

I was under the impression that the pagefile and virtual memory are one in the same.

When I change the virtual memory setting in XP, it has nothing to do with physical RAM.

If you have physical RAM it's no longer virtual memory because it's actual memory.

Nope, virtual memory is everything. Page file is part of virtual memory. All programs work with virtual memory. Windows determines whether the data is stored in pagefile or in physical memory. Think of it that way - memory accessible by programs is on page file, and RAM is used as cache, where most frequently accessed pages are held.

I still think you're wrong.

In what way? I took OS design class in college and this is what they taught us.

By definition, virtual memory can't be a physical memory. You have virtual memory (paging file because it acts like RAM) and physical memory.

I also stand by my comment that no where in Windows does it lump the two together. When you go to the virtual memory box in advanced tab of the performance settings it mentions NOTHING of physical memory, but only virtual memory and a paging file.

read up a little on OS and memory management.

Then you can read up on windows and memory management.

And than you'll see what we're talking about. windows only works with virtual memory, and that includes physical and page file.

 

[Rainsford]

Originally posted by: Argo

Originally posted by: pulse8

Originally posted by: Argo
Technically he's right, he just could've put it better. Virtual memory is total memory available to your programs, it's the total of physical memory and your page file.

I was under the impression that the pagefile and virtual memory are one in the same.

When I change the virtual memory setting in XP, it has nothing to do with physical RAM.

If you have physical RAM it's no longer virtual memory because it's actual memory.

Nope, virtual memory is everything. Page file is part of virtual memory. All programs work with virtual memory. Windows determines whether the data is stored in pagefile or in physical memory. Think of it that way - memory accessible by programs is on page file, and RAM is used as cache, where most frequently accessed pages are held.

From an engineering perspective you are correct. Your computer adresses things using virtual memory addresses which are then translated into physical memory addresses...the swap file/page file stores information that is "less used" (lots of algorithms are used to figure this out). If the virtual address is requesting a page that's not in physical memory, it is fetched from the page file into physical memory where it is read by the system.

Your programs don't know about all this, they only see the virtual memory address. So technically your tech support COULD be correct. The problem is that MS has sort of perverted this definition to mean "page file". It's all confusing, but I'd say most tech support people don't know how memory systems work in an OS, so it's a toss-up what the really meant.

 

[pulse8]

Originally posted by: spidey07
read up a little on OS and memory management.

Then you can read up on windows and memory management.

And than you'll see what we're talking about. windows only works with virtual memory, and that includes physical and page file.

Why should I read up on anything when it's already been addressed in this thread?

 

[johnjbruin]

well - OP - i think you might be wrong in this case. all the people talking about OS memory management make sense to me - cause i took those OS classes too. Maybe you should too - rather than basing your definition off of windoze.

 

[Woodchuck2000]

This, of course, begs the question: If virtual memory is just the page file, what's the name for page file plus physical memory (i.e. the total amount of memory available for an application to use)? Don't say 'total memory' as you won't find it used anywhere.

No-where (at least in XP) will you find 'Virtual Memory' used to describe the page file alone. It's logical if you think about it. If you turn off the page file then Virtual Memory == Physical Memory.

 

[Fandu]

Sorry to burst your bubble, but the technical folks are correct. It's only called virtual memory because windows gives programs virtual memory addresses to use and it then decides based on the number of accesses or prefetch algorthyms what data is placed into physical RAM and which is placed in the swap file.

In the case where you set the page file to zero size, then physical memory size = virtual memory size, but the addresses are still not the same. Your programs still use virtual addresses which are then remapped to physical memory.

Take a couple university CS courses, this is only second year material.

 

[PlatinumGold]

bottom line is, even were the tech people wrong, they weren't wrong be enough to warrant the OP. it's not like they said Virtual memory = total Hard Drive capacity. then it's worth this thread.

this is closer to if they had said, it is better to turn your PC off at night. where there really is no clear right answer.

 

[Nothinman]

Why should I read up on anything when it's already been addressed in this thread?

Because there's a lot of misinformation here and it can be hard to pick out the bad stuff. Essentially Rainsford is correct, on a 32-bit system the amount of VM available is always 4G per process, on Windows 2G is reserved for the kernel and 2G is available to every process seperately. During a context switch the VM mappings from process A are stored and replaced with the mappings for process B, the virtual addresses could point to anything the OS can handle be it physical memory on the local machine, a pagefile slot, a tape drive, physical memory on another machine, etc.

 

They know less than you and get paid more.

 

[Nothinman]

They know less than you and get paid more.

I wouldn't say that, the OP never said what he thought VM really meant, just that he thought their definition was wrong.

 

[her209]

Originally posted by: Nothinman

Why should I read up on anything when it's already been addressed in this thread?

Because there's a lot of misinformation here and it can be hard to pick out the bad stuff. Essentially Rainsford is correct, on a 32-bit system the amount of VM available is always 4G per process, on Windows 2G is reserved for the kernel and 2G is available to every process seperately. During a context switch the VM mappings from process A are stored and replaced with the mappings for process B, the virtual addresses could point to anything the OS can handle be it physical memory on the local machine, a pagefile slot, a tape drive, physical memory on another machine, etc.

This man speaks the truth.

VM does not equal page file. Think of the page file as RAM (on the hard drive).

 

[Nothinman]

The pagefile can't be compared to RAM because it's not accessed like that, it's basically a repository for memory pages that have been relegated to disk for some reason. In order to be used they have to be paged back into memory from the pagefile, if the CPU could access pagefile slots like physical memory pages the comparison would work but that's not the case.