S. Rao on 5/13/07 wrote:
---------------------------
>Well, IMHO, Intel simply didn't want to release a
>64bit extension to x86 because they wanted to maintain
>segmentation between IA64 and x86... so PAE was a
>handy kludge they could point to for the growing fraction
>of users with larger memory needs.

Agreed. But it almost certainly wasn't an engineering decision.

>Well, I think he's trying to say after that you have to
>start making serious performance tradeoffs...(I should
>probably just shut up and let him answer)

Yes. I didn't realize this was the case for 1 GB. All popular press gives the impression that you only need 64bit after 4G, so I guess I just accepted it without much thinking. Even though I should know better. In my previous job I had hell of a time having to fit lots (hundreds of megabytes) of memory-mapped hardware into Windows kernel space. IIRC, W2K had very limited number of system PTEs reserved for that.

Are you aware of any benchmarks that show the difference in performance between 32-bit and 64-bit with < 4GB, that can be attributed to the overhead of the kernel switching HIGHMEM pages ?


regards,
Tzvetan