On Dec 5, 2008, at 7:18 PM, Rainer Duffner <rainer at ultra-secure.de> wrote: > > Am 06.12.2008 um 01:02 schrieb Ignacio Vazquez-Abrams: > >> On Fri, 2008-12-05 at 23:57 +0000, Michael Holmes wrote: >>> 2008/12/5 Matt <lm7812 at gmail.com>: >>>> I have a server running Centos 4.7 32bit. Will moving from 4Gig of >>>> RAM to 8Gig do any good? Since its 32bit I assume it will only be >>>> able to address the first 4Gig not? >>> As long as you are using a SMP kernel you can use up to 64GB of RAM >>> (though each proccess can only address 4GB of this). So if you can >>> find any trace of "SMP" in the uname (grep is your friend) then it >>> should work fine. >> >> PAE, not SMP. >> > > > He should be able to replace the kernel via rpm -e and rpm -i > > That said, I doubt he'll actually see a benefit. > PAE is slow. > If you want to see a real performance-gain, install 5.2 x86-64. He'll see a benefit. PAE slowdown is humanly unnoticeable for short- term transactions, it's difference is in high nano seconds or low micro seconds. All 5.0 kernels are PAE by default. So are WinXP_SP2/Win2K3/Vista/Win2k8 and Mac OS X kernels. Only go 64-bit if it's completely necessary. -Ross