Chris Barker writes:

I don't understand mmap at all. From the name, it sounds like the entire contents of the file is mapped into memory, so the memory would get used as soon as you set it up. If anyone knows, I'd like to hear...

This might be more than you need to know, but there's a copy of the article: "Why aren't you using mmap() yet?" by Kevin Sheehan at: http://thrush.eos.ubc.ca/users/phil/mmap/mmap.pdf (note reversed page order) and a Solaris/SGI email debate in mhonarc format: http://thrush.eos.ubc.ca/users/phil/mmap/threads.html bottom line: you really need a vm implementation that supports madvise() to get the maximum benefit from mmap. (Linux 2.4 might have madvise, I haven't tried it out yet -- 2.2 didn't). The way I used to use mmap was through a numpy array class that was initiated from a pointer to a mmap'd file. This made reading/writing to the file as simple as indexing into the numpy array. I haven't been back to reimplement that class on linux since I left solaris, though. You can also get some of the benefits of mmap via netcdf, which will use mmap if it exists. Regards, Phil