Re: OT - Shutting down an RS/6000 ?

[Hans Boldt <boldt@xxxxxxxxxx>]

James Rich wrote:
> On Fri, 15 Nov 2002, Hans Boldt wrote:
> > Joe: The same issues of inter-program communication affect
> > programming in most OS's, as far as I can tell. But again, OS/400
> > seems to be the odd one out in that parameter passing between
> > programs can indeed be bidi. The single level store probably has a
> > lot to do with that, since programs running in different processes
>
> I just had a thought on this:  can't the same thing (passing parms from
> one executable to another and back again) be achieved using mmap?  I
> haven't ever coded anything that used mmap and it might be a kernel
> space only function.  But it does give a type of single level store for a
> limited memory space (meaning that two apps access the same memory area).
Just my two cents worth:

I suppose you could use mmap() if you really wanted to. But then
you'd also have to deal with issues like process synchronization.
Considering how easy it is to program interprocess communications
via pipes in the average high-level "scripting" language, I'm not
sure why someone would want to use a low-level function like mmap()
in a typical application.

Even for random processing within a file, a file would have to be
pretty big these days before mmap() would be preferable over loading
the entire file into RAM.

(On the other hand, I can certainly think of lots of uses of mmap()
for *systems* programming.)

Cheers!  Hans