mmap « malloc « C Q&A

1. Will malloc implementations return free-ed memory back to the system?    stackoverflow.com

I have a long-living application with frequent memory allocation-deallocation. Will any malloc implementation return freed memory back to the system? What is, in this respect, the behavior of:

• ptmalloc 1, 2 (glibc default) ...

2. mmap regions allocating from reserved stack space?    stackoverflow.com

In our product we use a malloc implementation that relies exclusively on mmap for memory allocation. We also do a fair use of allocaing. We've just encountered a problem ...

3. how does mmap work?? I mean, what kind of problem can make it fail    stackoverflow.com

I am working on programs in linux which needs mmap file from harddrive, but i have a question, what can make it fail. like if all the memories are fragmental, which ...