Using Memory Mapping or Unlocked Stream Operation?

I am working on a FUSE implementation for FAT32 under Linux (I know this is already available in the Linux Kernel, but this is a school assignment). The FAT32 f开发者_Python百科ilesystem is created with the mkfs.msdos command, which I will later map into memory with posix_madvise, or use an unlocked stream by means of posix_fadvise.

I am not sure what should I base my choice on, I mean, what the pros and cons of each method are (in terms of performance, memory usage, etc). I have seen a few examples out there which combine the use of madvise with mmap, but no information was provided as to whether fadvise should be used with mmap too, or, to start with, the difference between the fadvise/madvise and POSIX implementations posix_fadvise/posix_madvise.

Any point in the right direction will be greatly appreciated.

Unless you want to limit yourself to ~2.5 GB filesystems or requiring a 64-bit machine, your choices are to use mmap and dynamically manage what part of the filesystem you keep mapped, or use normal read/write operations. I would probably go for the latter. mmap is overrated as a performance optimization, and has drawbacks like filling up your virtual address space, so I would tend to only use mmap when you really need to treat a file as memory - for instance, storing process-shared synchronization objects, executable code, or large data you want to feed to an API that only accepts in-memory data (for example, qsort).