Re: Is OpenLDAP PAE Aware?

[Robert Heller <heller@deepsoft.com>]

At Fri, 13 Feb 2015 10:47:31 -0500 Brian Reichert <reichert@numachi.com> wrote:

> 
> On Fri, Feb 13, 2015 at 03:43:25PM +0000, Jack Kielsmeier wrote:
> > I suppose I should also mention the older version of OpenLDAP we are running. It's openldap-2.4.17.
> 
> We've run OpenLDAP on a PAE host with 6G of memory.  PAE only affects
> how the kernel tracks pages of memory; a userland process doesn't
> care.

Right. PAE is just a way for a *32-bit* system, with a 32-bit address space:
4G, less system overhead (eg PCI bus addresses, etc.) to make use of more than
3.5G of *physical* memory. It is also used when a 64-system is running with a
32-bit operating system (32-bit kernel). Only the kernel knows about PAE.
Userland processes only see a 32-bit address space. OpenLDAP, like any other
userland process is NOT ever 'PAE Aware', although if you are running a 32-bit
version of OpenLDAP on a 32-bit operating system (kernel) on PAE hardware and
if the kernel is built with PAE support, the PAE hardware will be used, but
OpenLDAP won't be aware if it in any sense -- it will just see upto all of
about 3.5G of memory and will totally unaware that *other* processes (and the
kernel) will be using other memory (as if the kernel and the rest of the
system somehow were using no physical memory at all).

> 
> A single process is still capped, more or less, at 3G:
> 
>   http://www.spack.org/wiki/LinuxRamLimits
> 
> > Jack Kielsmeier
> > Systems Engineer
> > 
> > 
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