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Re: Using vfork() in do_system() instead of fork()


On Tue, 23 Jun 2009 14:51:37 -0700
David Wuertele <dave+libc-help@wuertele.com> wrote:

> >> > i can almost guarantee you that drepper would tell you to go away,
> >> > especially because your "problem" only manifests when you've turned off
> >> > over commit.
> >>
> >> I didn't realize there was a recommended overcommit setting with glibc.
> >> I tried looking for documentation of that, but I can't find it.
> >
> > you have a MMU, use it
> 
> Sure, that would be any sane programmer's preference.  But on this point
> I am at the whim of other users of the system.  I wonder if my constraint is
> really that unusual?
> 
> As long as the Glibc authors/maintainers don't specify a supported or
> recommended value for the overcommit setting, I think it is reasonable
> to expect system() to work even if my process has already malloced
> more than half of available ram, don't you?

I mentioned this trouble yesterday in a rather cynical chat room (without being too specific) and got back something about "cargo cult programmers." :/  Un*x in general has got where it is by *not* being the kind of operating system where you can poke about with stuff and expect the OS to clean up after you. It's fragile.

The reason un*x operating systems are fragile is because fragile software can do a whole lot more with a whole lot less. IIRC a slogan of early unix-based systems was "90% of the capability for 10% of the price." It quite deliberately doesn't quite cover all bases because if it did it would take far more powerful hardware to run it.

C is fragile; pointers, null-terminated strings, and (for crying out loud) void pointers are not tools which can be applied in all situations without care. It's not really a very nice language, but it's set the standard for performance hasn't it?

-- 
Ethan Grammatikidis
The lyf so short, the craft so long to lerne. -- Chaucer


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