Re: Arbitrary Sandbox

["Randy Brukardt" <randy@rrsoftware.com>]

"Robert A Duff" <bobduff@shell01.TheWorld.com> wrote in message 
news:wccr4xpnkh6.fsf@shell01.TheWorld.com...
> tmoran@acm.org writes:
...
>>   BTW, the only real problem we had with bad user programs was one grad
>> student who had heard about "virtual memory" and wrote his program to use
>> large arrays.  Unfortunately he accessed them column-wise, while they 
>> were
>> stored row-wise, so his program swapped horribly.  In 1970 it would have
>> taken a very smart compiler indeed to prevent that problem.
>
> That problem still exists.  I've seen cases recently, on both windows
> and linux, where a rogue program swapped horribly, and put the system
> in a state where it won't listen to the keyboard or mouse, so I can't
> kill the program.  It seems to me it's possible to design an OS that
> wouldn't do that.

Indeed, until I got rid of them, there used to be a bunch of ACATS tests 
that *tried* to exhaust memory, and thus often had that effect. I remember 
that we had to put an artificial memory limit into our early Windows NT 
compilers to keep those tests from crashing our solitary Windows NT machine 
(which also doubled as our domain controller, so that was not good.).

One of the first things I did when I took over the ACATS was to get approval 
to remove those tests from the test suite. (I think I actually ended up 
allocating a large data structure, but bounded the size to 32MB, rather than 
just running until Storage_Error was raised.)

                                  Randy.