[Lustre-discuss] page allocation failure

Alex linux at vfemail.net
Fri Nov 28 01:14:47 PST 2008


On Thursday 27 November 2008 20:30, Andreas Dilger wrote:
> On Nov 26, 2008  19:04 +0800, Wang lu wrote:
> > The %util of memory on OSS was always around 10% ,even when OSS was going
> > to die.
> >
> > The OSS kernel is:
> >  2.6.9-67.0.7.EL_lustre.1.6.5smp(32bit)
> >
> > Lustre version is 1.6.5.1
> >
> > We have 8GB physical memory and 16GB(never been used) swap total.
> >
> > Is there a problem with memory management?
>
> The problem is with the 32-bit kernel.  Linux doesn't allow a 32-bit
> kernel to use more than 900MB of memory on a 32-bit system, no matter
> how much RAM is installed.  900MB/8192MB ~= 10% of RAM.  

I want to clarify this, because i don't understand why are you saying that it 
can be used max 900MB of our RAM! Afaik, on 32bit system, we have the 
following limits:
- max 4GiB RAM using kernel without PAE (Physical Address Extension)
- max 64GiB RAM using kernel with PAE (extend physical address size from 32 to 
36bits)

> Swap is not 
> useful for the kernel.
>

Why?

Regards,
Alx



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