[cmucl-help] maximum dynamic-space-size

[Tom Mitchell]

On Tue, Jan 5, 2016 at 6:25 PM, Matt Kaufmann <kaufmann at cs.utexas.edu>
wrote:

> Thanks for the reply.  I like the idea of "0" meaning "max"; I'll
> probably take advantage of that if you make that change.  In the
> meantime, it's good to know that there isn't any other way to figure
> out the max besides parsing it out of that error message.
>
....

> > From: Raymond Toy <toy.raymond at gmail.com>
> > Date: Tue, 05 Jan 2016 16:14:55 -0800
> >
> > >>>>> "Matt" == Matt Kaufmann <kaufmann at cs.utexas.edu> writes:
> >
> >     Matt> Hi --
> >     Matt> Is there an easy way to figure out the maximum value that can
> be
> >     Matt> supplied for CMUCL command-line option -dynamic-space-size on
> a given
> >     Matt> platform?  Or perhaps some special value could be allowed for
> >     Matt> -dynamic-space-size that means "use the maximum"?
> >
>

Is there a way to protect from the Linux kernel  overcommit option?
One real problem when overcommit is set to true is long running
programs can run out of resources hours and days into a run.
Compare malloc()  and calloc() and how errors are handled when
system limits or system resources are exhausted.

The value of overcommit is that a large long running job can
do a fork(); exec() pair where the exec is a smallish process like
print.answer.   The duplicated pages from the fork() and the associated
bookkeeping cause no harm because copy on write never happens.

The notion of "maximum" is almost never correct on shared commons
computing systems which is today's most common systems.

*$*sysctl -a | grep overcom
vm.overcommit_kbytes = 0
vm.overcommit_memory = 0
vm.overcommit_ratio = 50






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