[Info-vax] OpenVMS I64 V8.1 "Evaluation Release"?

[John Wallace]

On Mar 23, 12:30 pm, Paul Sture <p... at sture.ch> wrote:
> On Thu, 22 Mar 2012 22:33:26 +0000, glen herrmannsfeldt wrote:
> > Reminds me, though, of once trying to figure out how much virtual memory
> > was available by allocating it and counting. Then, on an HP-UX machine,
> > tried:
>
> > for(; malloc(1000);
>
> > which, after not so long, crashed the machine.
>
> > (I am not sure of the exaxt number in the malloc, but at some point the
> > system couldn't allocate memory for some important use and just gave up.
> > You aren't supposed to be able to crash unix running as an ordinary
> > (non-root) user, but sometimes.)
>
> Again on my old iBook, one of my early attempts to manipulate strings in
> a tight loop using Objective-C resulted in a serious memory leak.  That
> put the system in an extremely unstable state, and yes, I was running as
> an ordinary user.  Hitting the power button was the only way out.
>
> --
> Paul Sture

Denial of service through shared resource exhaustion, or the avoidance
thereof, is part of why VMS has lots of separately manageable quotas,
and a specific privilege to allow quota checks to be overridden. VMS
sysadmins can largely ignore these quotas if they wish, and often do
without much adverse effect. But where it matters, sysadmins have the
option to manage quotas securely if they so desire, an option which
few other OSes offer.

The downside of this is that some operations on VMS incur a quota-
accounting (and privilege checking) overhead which slows them down
slightly relative to the equivalent operation on a no-quota OS which
doesn't have fine-grained privileges. But there is no such thing as a
free lunch.