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Proposal for instruction set - now on Github
Author:  Date: 2016-09-05 18:33
There's more to mmap:

- It's can be used to allocate memory, page by page (for instance as a back-end for malloc()).
- It can be used to memory map hardware devices. For instance, sometmes video device VRAM is mapped by mmap()ing /dev/mem at 0xa0000.
- It can be used for inter-procedure shared memory: if multiple programs mmap() the same file, they will actually get a mapping to the same block of RAM.
- The fork() function relies on paging to do a shallow copy of the whole memory space, and then selectively does a real deep copy of a page when one of the forks writes to it and triggers a page fault.
- Demand paging of newly allocated memory lets the OS deal with badly behaved memory allocators, for instance when the Java virtual machine allocates 512mb of ram on startup. Executable data of large shared libraries like QT can also be loaded on-demand this way.
- When RAM runs out, mmap()ed memory that is backed by disk files and doesn't need to be written to swap-space can be priorized.
- Also, mmap() also works well with SSDs.

 
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