windows - Reading huge files using Memory Mapped Files

Question

I see many articles suggesting not to map huge files as mmap files so the virtual address space won't be taken solely by the mmap.

How does that change with 64 bit process where the address space dramatically increases? If I need to randomly access a file, is there a reason not to map the whole file at once? (dozens of GBs file)

Answer 1

On 64bit, go ahead and map the file.

One thing to consider, based on Linux experience: if the access is truly random and the file is much bigger than you can expect to cache in RAM (so the chances of hitting a page again are slim) then it can be worth specifying MADV_RANDOM to madvise to stop the accumulation of hit file pages steadily and pointlessly swapping other actually useful stuff out. No idea what the windows equivalent API is though.