AFAIK, Task Manager in windows 2008 shows the physical memory. I have a program that sums up the FREE physical & FREE virtual memory in MG.

How can I confirm it has the right output of this sum? the physical I can take from task manager at the same second, but where do I take the virtual from? performance counters or something?

  • There is really no such thing as "free virtual memory". Modern operating systems can create massive amounts of virtual memory on demand. For example, start a 64-bit process, memory map an 8GB file, and you now have 8G more virtual memory in use. When you remove that mapping, you don't have 8GB of virtual memory that's free, the virtual memory ceases to exist. "Free virtual memory" is really equivalent to nothing at all. When a process terminates, does its VM become free? No, it ceases to exist. – David Schwartz Feb 4 '14 at 18:08
  • Thanks. so what is this Free Virtual MEmory that OS supplies in this link - msdn.microsoft.com/en-us/library/windows/desktop/…? – user1025852 Feb 4 '14 at 21:41
  • According to the part of that web page that makes sense, it's how much the commit charge can grow before the OS would have to overcommit to allow it to grow -- free RAM plus unused paging file space. This is gobbledygook though, "Number of kilobytes of virtual memory currently unused and available." (For the reason I explained. Are file mappings virtual memory? Of course they are.) – David Schwartz Feb 4 '14 at 22:39

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