[GRLUG] 64-bit Linux

[Michael Mol]

On Fri, May 9, 2008 at 2:31 PM, Collin <adderd at kkmfg.com> wrote:
>>
>>
>> Any x86-64 processor should have Intel's Paged Address Extensions,
>> giving 32-bit operating systems access to up to (IIRC) 64GB of RAM.  I
>> know it's possible on Linux, at the very least. See the "64GB high
>> memory" option if you configure and compile your own kernel.
>>
>> I like x86-64 primarily because of the 8 GPRs that the compiler can
>> optimize for, instead of 4 GPRs on IA32.  I've done enough performance
>> coding to recognize how useful it can be to have that many more places
>> to store values and pointers, and avoid needing to call out to cache.
>>
>>
>
> That's true. PAE has been available on a lot of intel processors for
> some time now. But, quite frankly, it sucks. The processor can't
> physically access all of that memory in one shot so you end with a lot
> of wrangling in page tables. It slows down the system performance. If
> you are going to slow down the performance anyway then you may as well
> go to 64 bit where sometimes it might actually be faster instead of slower.

Hey, at least PAE (paging to RAM) was faster than virtual memory
(paging to disk). :-)

-- 
:wq