Re: Limiting the amount of memory an application can allocate

[Rigoberto Corujo <rcorujo yahoo com>]

Thank you for your response John.

> The resident set size, rss, is the maximum amount of
> virtual memory resident in real memory.

Would you be able to explain what "maximum amount of
virtual memory resident in real memory" means?

> RLIMIT_DATA corresponds to ulimit -v, I believe.

I think RLIMIT_AS corresponds to "ulimit -v" and,
unlike "ulimit -m", a call to getrlimit using
RLIMIT_AS will return the value set by "ulimit -v".

Anyway, I'll keep poking at it.

Thanks again for your quick response.

Rigoberto Corujo


--- John Haxby <jch scalix com> wrote:

> Rigoberto Corujo wrote:
> > If my crude method for estimating the physical
> memory
> > used is reasonably correct, you can see that 1 Gig
> of
> > memory was allocated even though I had set "rss"
> in
> > "limits.conf" to 10 Meg.
> >
> >   
> The resident set size, rss, is the maximum amount of
> virtual memory 
> resident in real memory.  If you started writing to
> that 1G buffer (eg 
> with memset()) you'd notice a few things: it runs
> very, very slowly; 
> "top" will report an RSS of 10M; the system will be
> running at 100% 
> iowait and it will mostly likely be very
> unresponsive.
> 
> VMS used to (and maybe still does) play silly
> buggers with allocating 
> only a small amount of physical memory for process's
> working set size -- 
> which should immediately tell you where they went
> wrong :-)  I used to 
> get much better overall system performance by
> bumping up the maximum 
> working set size and leaving the quota quite low. 
> Ahhh ... takes me 
> back ...  The upshot is that if you limit the rss of
> a user's processes 
> then you may well wind up making the system
> performance much worse.
> 
> > One thing I can't figure out is why the call to
> > getrlimit is saying that RLIMIT_DATA is unlimited
> when
> > "ulimit -m" is telling me that it is set to 10
> Meg.
> >   
> RLIMIT_DATA corresponds to ulimit -v, I believe.  
> But note that this is 
> a per-process setting.  If you're trying to stop
> some user eating all 
> the physical memory in some huge emacs process, for
> example, he (or she) 
> can still eat all the physical memory by running
> lots of 
> not-quite-so-huge emacs processes.   You're probably
> better off going 
> round with a Big Stick and "persuading" him (or her)
> to behave.
> 
> jch
> 
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> 



       
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