UNIX semantics do permit full support for asynchronous I/O

[bruce.d.szablak]

In article <1990Aug29.170931.10853 at terminator.cc.umich.edu>, rsc at merit.edu (Richard Conto) writes:
> In article <27619 at nuchat.UUCP> steve at nuchat.UUCP (Steve Nuchia) writes:
> >Have read(2) and write(2) calls map the pages containing the buffers
> >out of the user address space and return immediately.
>  
> A buffer is not necessarily aligned on a page boundary. And a page
> may contain more than one variable.

Actually, the OS only has to mark the pages as copy on write. This sort
of thing is often done when a process forks to avoid making a copy of the data
space for the child. Whether its worth it is another matter.