Re: Interesting things from the Plan 9 rc manpage

[jeremy@sw.oz.au (Jeremy Fitzhardinge)]

Paul Haahr bubbles:
> > A new process would share the namespace of its parent, including /env,
> > so there's no work that needs to be done by any party.
> 
> yes, but a shell typically reads its entire environment on startup, and
> all those readdir(), open(), read(), and close() operations can't be free.
> on the other hand, if they don't cache the environment in the shell,
> every reference to an environment variable has to do 3 system calls
> (open, read, close), which is painful in my mind, but maybe rob's right
> when he says you shouldn't worry about system call overhead.
> 
> thinking about it, they probably have to use the latter approach, because
> otherwise you can't take advantage of the sharing of environments between
> processes that plan 9 offers.

Despite Pike's well known resistance to memory mapped files, this looks
like at least one pretty good application for them.  Really, that's
what segattach() is, but it has its own special name-space (the class),
rather than going through the filesystem namespace.  True, that's not the
intent, but it loses generality to be otherwise.  Are we off topic yet?

> anyway, this is all idle speculation.

Fun, isn't it?  Need something to fill a mailbox while people stop arguing about
job control in es.

	J

-- 
jeremy@sw.oz.au ph:+61 2 698 2322-x122 fax:+61 2 699 9174
While the earth dies dreaming, I lie screaming.