Memory usage of a process

[Günter Leonhardt]

Hello,
analysing the memory usage of a process, I found some questions.
I'am using a system with 128 MB physical RAM, no disk, 2.6.27 kernel.

Running top, I see 38 MB in use, 90 MB free, but a VSZ for my process of 158 MB.
Looking at /proc/<pid>/maps, I see that the process uses 140 MB without shared libs.

So how it is possible that the process can allocate more memory than there is, without posibility of swapping?

Why said top that 90 MB free? Does the kernel serve the allocation only if ist really used?

Günter