On Wed, 03 Dec 2014 08:42:27 -0800 Thiago Macieira <[email protected]>
said:

> On Wednesday 03 December 2014 10:36:26 Dominig ar Foll wrote:
> > the model that I have used in previous project was to check have the
> > ressource manager to try to allocate the memory amount considered to be
> > the healthy minimum for a very short time an to release it.
> > That model also allow to check that not only memory is available but a
> > decent amount of continuous memory can be allocated.
> 
> Contiguous memory does not make sense in userspace. One contiguous block of 
> virtual memory can be backed by a series of discontiguous pages. And there
> are very, very few legitimate uses of contiguous physical blocks of memory
> and they're all related to hardware.
> 
> I don't recommend trying to allocate memory to check if you can allocate 
> memory, as you may cause the very problem you're trying to prevent (suppose 
> something else tries to allocate a healthy amount of memory at the same
> time). Besides, you have to fault in all of those pages to make sure you
> actually got them, which will imply CPU usage...

and if you happened to run out of memory where linux over-allocated during
faulting... you need to handle your sigbus you'll get and avoid your crash
too... otherwise your resource daemon will no longer be... :)

> -- 
> Thiago Macieira - thiago.macieira (AT) intel.com
>   Software Architect - Intel Open Source Technology Center
> 
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-- 
Carsten Haitzler (The Rasterman) <[email protected]>
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