I think that the reason for installing PAE kernel as a default is because the No Execute (aka NX bit) CPU feature is available only when the CPU is configured to PAE mode. AFAIK the other OS from Redmond also uses PAE by default (using the ntkrpamp image).
I don't know about performance implication of PAE, but i assume it is minimal: It is supported by the CPU HW. When PTE is ebabled, the CPU page tables are changed slightly to support a bigger address space. The difference is in the PGD and PTE structures (IIRC there is another middle PMD struct when in PAE mode). All the page table entries are cached by using the TLB, so you should not see any real performance difference. Also, i don't think going x64 will improve anything (especially if you dont really need a 64 bit address space) - it will only make your programs consume more RAM. On Sun, Aug 2, 2009 at 23:46, Oron Peled<o...@actcom.co.il> wrote: > On 02.08.2009 Hetz Ben Hamo wrote: >> The Fedora 11 default installation installs the kernel with PAE >> installation *regardless* of how much RAM I have. >> >> I was wondering: are there any performance "penalties" when using PAE >> enabled kernel instead of the i686 version? > > Two links with some more reasoning/info: > http://thorstenl.blogspot.com/2009/05/fedora-11-kernel-pae-and-what-it- > means.html > https://fedoraproject.org/wiki/Features/ArchitectureSupport > > -- > Oron Peled Voice: +972-4-8228492 > o...@actcom.co.il http://users.actcom.co.il/~oron > ... Complex problems have simple, easy to understand wrong answers. > > > _______________________________________________ > Linux-il mailing list > Linux-il@cs.huji.ac.il > http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il > -- Marie von Ebner-Eschenbach - "Even a stopped clock is right twice a day." - http://www.brainyquote.com/quotes/authors/m/marie_von_ebnereschenbac.html _______________________________________________ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
