[CentOS] To PAE or not to PAE...

Thu Jul 22 11:48:45 UTC 2010
Peter Kjellstrom <cap at nsc.liu.se>

On Thursday 22 July 2010, John Doe wrote:
> Hi,
> I was wondering if anyone would know the cons of running a PAE kernel...?
> I have a 4GB pc and was wondering if it was worth going the PAE way to gain
> those exta 700MB...
> In the past, I heard that these 700MB were normally reserved for bios or
> chipset stuff...
> And that running in PAE would slow down some processes.
> By the way, I know 64 bits would solve this dilemn but right now I am
> 32bits...

There is no general answer. Getting more memory could for some workloads be 
critical. On the other hand, other loads might not care much about the extra 
few hundred megs but instead suffer some PAE related slowdown.

Good news though, trivial to test. Just reboot with the PAE kernel, check the 
performance of your workload. If you see improvment stay on PAE, else go 

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