Task Manager and memory usage

I'm a little bit confused about Task Manager and usage memory.

Is the sum of all memory processes equal to the physical memory used?

This is a picture of my Task Manager ordered by memory usage high to low:

This is a screenshot of the physical memory used at the same time:

However, the sum of all the memory processes is less than the ~11 GB shown in the second picture.

Which is the true usage?

The OS is Windows Server 2003 Enterprise Edition 64-bit (running on a virtual machine with four CPUs and 24GB RAM)

Solution 1:

There is an overlap in memory used by your applications. When an application is using a DLL, which is a shared library, the library is loaded into the physical memory only once, but every application using it sees an increase in its own memory usage. The Wikipedia article on shared libraries explains memory sharing quite well.

I see that your Windows is not in English, but if you try to translate the fields, I hope this information will help (taken from my Windows 7). The resource monitor can display working set, shareable memory and private memory for each process. Shareable memory and private memory are both combined into the working set of the application. Resident set is part of working set which is in physical memory (RAM) as opposed to being swapped on the hard drive.

So each shared library contributes towards the shareable memory of each application, which is a part of the working set. You have added up all working sets of all applications, I believe.