Re: [SOLVED] Is my processor 32-bit or 64-bit?
shawn wilson <ag4ve.us@gmail.com> writes:
> On Tue, Aug 28, 2012 at 1:34 AM, Bob Proulx <bob@proulx.com> wrote:
>> Stephen Powell wrote:
>>> By the way, there's something I don't understand. A 32-bit processor can
>>> only access 4G of "real" (extended) memory, right? So why are there
>>> motherboards available for 32-bit processors that support installing
>>> more than 4G of RAM? What good is memory that the processor can't address?
>>
>> With PAE (physical address extensions) the processor *can* address
>> more than 4G of ram. A single process is still limited to 32-bits
>> which usually works out effectively to 3G of ram but the operating
>> system can make use of more than this. It can be used for filesystem
>> buffer cache and for multiple 3G programs. A machine with 6G of ram
>> for example could run two 3G program at the same time and hold them
>> both in memory without swapping. Or run one 3G program and still have
>> 3G for the system to use in filesystem buffer cache. With PAE having
>> more than 4G of memory is quite useful.
>>
>> Using PAE does have a small performance impact. It slows things down
>> by 2%-3% in my use cases. But the increase in ram for buffers usually
>> more than makes up for the differences.
>>
>
> iirc, pae is only 48 bits too.
"only" meaning 256 terabytes in this case... I'll be very surprised to
ever see a 32 bit processor that can make effective use of that much
memory.
--
"Erwin, have you seen the cat?" -- Mrs. Shroedinger
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