Re: -mmX 4G patches feedback [numbers: how much performance impact]

[Manfred Spraul]

Arjan wrote:

> afaics all Intel and AMD cpus with more than say 32 or 64 TLB's are
> actually 64 bit capable.... so obviously you run a 64 bit kernel there. 
> (and amd64 even has that sweet CAM filter on the tlbs to mitigate the
> effect even if you run a 32 bit kernel)
Does AMD document how the CAM filter actually works? x86-64 writes into 
the 4th level page table during a context switch and if I understand the 
patent description correctly, this defeates the flush filter and forces 
a full flush during a context switch.

--
   Manfred

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