Re: Exceptions, Go to Hell!
On Aug 26, 12:14 pm, =D6=F6 Tiib <oot...@hot.ee> wrote:
On Aug 26, 1:28 pm, James Kanze <james.ka...@gmail.com> wrote:
[...]
That overcommit is red herring since it can be turned off
with some kernel parameter like "vm.overcommit_memory
= 0". If an user refuses to turn it off and random apps he
runs get killed randomly then it is his fault, why should
you care.
Whether it can be turned off, and how, depends on the
OS---Linux isn't the only one which overcommits.
Yes, but do you know one where it is on and can not be turned
off?
I've known some in the past. (At least one has evolved to make
overcommit optional, turned off by default. And I think it can
be turned on at a process by process level, which is
a reasonable option.)
Linux is most widely accessible OS that has overcommit so
i gave it as example. Imagining OS that has overcommit
unavoidable i have to overtake memoy management/allocation,
take large chunk and fill with random numbers to be sure it is
mine. Using problematic platforms has a cost.
Yes. Where I was working at the time, our solution was to not
use them:-). Anytime you're doing something serious, which has
to work, then you cannot permit overcommit.
And a lot of Linux boxes are running in situations where
there isn't really a qualified sysadmin, who can be presumed
to know about such things. What is the value set to by
default on the distribution DVDs?
The ones i have some experience with had it set 0 by default.
I have quite limited experience with Linux so i do not know,
but having it on by default sounds like having some "run
unreliably" setting turned on by default.
If vm.overcommit_memory == 0, Linux uses "heuristic overcommit
handling", whatever that means (but it does mean
overcommitting). 1 means always overcommit, and 2 means don't
overcommit. If vm_.overcommit_memory is anything but 2, your
system is unreliable. (On the other hand, you may be able to do
more with it if it doesn't crash. Some programs do allocate
large blocks of memory that they don't fully use.)
--
James Kanze