Re: 2G memory split

[Jeff V. Merkey]

Alan Cox wrote:

> On Maw, 2006-01-10 at 09:56 -0700, Jeff V. Merkey wrote:
>  
>
> > RH ES uses 4:4 which is ideal and superior to this hack.
> >    
>
> Its a non trivial trade-off. 4/4 lets you run very large physical memory
> systems much more efficiently than usual but you pay a cost on syscalls
> and some other events when using the majority of processors. The 4/4
> tricks also give most emulations (eg Qemu) serious heartburn trying to
> emulate %cr3 reloading via mmap and other interfaces with high overhead
> in relative terms.
>
> Of course AMD64 kind of shot the problem in the head once and for all.
>
>  

Yep, they sure did.  Seriously, the 4:4 option should also be present 
along with 3:1 and 2:2
splits.  You should merge your RH work into this patch and allow both.  
It would save me one less
patch to maintain off the tree.

Alan, you're the man.

:-)

Jeff

> Alan
>
>
>  

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