On Tue, 29 Jul 2008 12:52:14 +0400, Enrico Weigelt <weigelt@metux.de> wrote:

Hi!

an full mmap() is a really nice thing. It can make a lot things
easier if you just map the whole file into the process' memory and
let the kernel handle the actual IO.

Yes, it is comfortable. But just think a bit - what will you do in the mmap implementation when you had mapped a remote file (in Plan9 you can't be sure some file is local or it is really just a file), and the connection has just been broken? Surprise!

For example, in Windows you will have an "access violation". It is very funny to rewrite a code for using the good old file i/o instead of mmap.
In Linux you can't map a non-regular file.

Yes, you can read entire the file into the memory, but a size of the file can be very big and you will destroy the main advantage of mmap - the reading of only needed pieces of the file, not entire.

I beleive, mmap is not for distributed systems.

--
Best regards,
       santucco