How can I measure the actual memory usage of an application or process?

Question

This question is covered here in great detail.

How do you measure the memory usage of an application or process in Linux?

From the blog articl

Answer 1

This is an excellent summary of the tools and problems: archive.org link

I'll quote it, so that more devs will actually read it.

If you want to analyse memory usage of the whole system or to thoroughly analyse memory usage of one application (not just its heap usage), use exmap. For whole system analysis, find processes with the highest effective usage, they take the most memory in practice, find processes with the highest writable usage, they create the most data (and therefore possibly leak or are very ineffective in their data usage). Select such application and analyse its mappings in the second listview. See exmap section for more details. Also use xrestop to check high usage of X resources, especially if the process of the X server takes a lot of memory. See xrestop section for details.

If you want to detect leaks, use valgrind or possibly kmtrace.

If you want to analyse heap (malloc etc.) usage of an application, either run it in memprof or with kmtrace, profile the application and search the function call tree for biggest allocations. See their sections for more details.