According to System Information:
Total Physical Memory = 8,189.35 MB
Available Physical Memory = 6.22 GB
Total Virtual Memory = 16.02 GB
Available Virtual Memory = 14.26 GB
Page File Space = 8.29 GB
Two questions rolled into one ... what is the difference between Virtual Memory and a Page File, and how is this different from Linux swap? Also, with a whopping 8 gigs of RAM, why are 2 full gigs used up of this virtual memory?
On Windows, a page file is a single file that acts as virtual memory, and is usually stored in the root of the filesystem. At first, Windows page files were just one file that expanded as needed to acommodate the data needed. However, these quickly became corrupt as the files grew and shrunk.
Thus, the way Microsoft does it now is it has a maximum size for a page file which you can manually set in the Control Panel (in this case it's 8.29 GB). It creates multiple files if the data stored exceeds the maximum size set for a page file. For you, you've got 2 page files, so then your total virtual memory is roughly 8.29 GB x 2 = ~16.02 GB.
And so in this example, since 14 GB is available, that means your first page file has used about 2 GB.
Hope this helps
But why am I using up 2 gigs of this pagefile if I have 8 gigs of physical DDR2 SDRAM with 6 gigs still available?
But why am I using up 2 gigs of this pagefile if I have 8 gigs of physical DDR2 SDRAM with 6 gigs still available?
*shrugs*
I think it may have to do something with Windows keeping data that doesn't need to be accessed right now in the hard drive cache so that other programs to access the physical RAM. But yeah, it doesn't really make sense when there's a whole 6 gigabytes available.
I just checked by Mac's memory usage, and it too uses virtual memory when there's still lots of physical memory available.
Two questions rolled into one ... what is the difference between Virtual Memory and a Page File
You are getting confused -- Paging is a mechanism used to implement the concept of virtual memory. Paging is a mechanism in which the entire virtual memory is divided into pages -- pages which on demand can be pulled in them physical memory as and when required and written to secondary storage when they are no longer needed (process is idle, etc.). A page table is used to maintain the mappings between the pages and frames i.e. for a chunk of data if it resides at a virtual address X then its physical address is Y and vice versa. Hence whenever data is moved out from the Physical memory or brought into it, changes need to be made to the page table.
and how is this different from Linux swap?
The main difference lies in their names. Swapfiles operate by swapping entire processes from system memory into the swapfile. This immediately frees up memory for other applications to use.
In contrast, paging files function by moving "pages" of a program from system memory into the paging file. These pages are 4KB in size. The entire program does not get swapped wholesale into the paging file.
Also, with a whopping 8 gigs of RAM, why are 2 full gigs used up of this virtual memory?
I think both you and Joey and confused as to what "Virtual Memory" actually stands for the physical memory of the computer plus the hard disk space which will be used for simulating the physical memory. If you want to know whether you are actually using your hard disk space as virtual memory or no, just look at the total memory usage -- its its greater than your physical RAM then yes you are using your virtual memory otherwise no. Virtual Memory -> Physical Memory + Hard Disk Space used to simulate physical memory If you think of it this way, the figures which you posted start making sense, don't they.. ?
reps for that post. I've never actually gotten the terminology fully explained to me before.
I know this is old, but why care about 2 gigs of disk space for whatever, when you have a large hard drive with lots of space left? Common sense people, maybe these two gigs are needed.
Yay for thread necromancy :P
If you want to know whether you are actually using your hard disk space as virtual memory or no, just look at the total memory usage -- its its greater than your physical RAM then yes you are using your virtual memory otherwise no.
This is not necessarily correct, as the OS could be aggressively swapping data into a pagefile. This would save time if the memory were later to be swapped out, so long as the page file is up to date.
I have used Google to find some explanation about Virtual Memory and page file ... have been lead to this thread, hmm.
The very question I was after, has been asked by cscgal:
With a whopping 8 gigs of RAM, why are 2 full gigs used up of this virtual memory?
Well, I have just registered with this forum, just to tell all those who have answered: WHAT CRAP ANSWERS !
I have yet to find something which kind of answers the question from above that way, that we're able to understand it somehow.
Mission impossible I guess.
I have used Google to find some explanation about Virtual Memory and page file ... have been lead to this thread, hmm.
The very question I was after, has been asked by cscgal:
Well, I have just registered with this forum, just to tell all those who have answered: WHAT CRAP ANSWERS !
I have yet to find something which kind of answers the question from above that way, that we're able to understand it somehow.Mission impossible I guess.
well i have just registered to this forum to tell you your wrong, this was a very informative thread.
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