32bit vs 64bit Linux

Fri May 31 10:41:57 MST 2013

> If you have more than 4GB of memory, you must use a 64bit kernel or the OS
> will not use the additional RAM over 4G.
Actually, you can access all your memory on 32 bits, that's the problem that 
PAE solves, at the cost of performance.
Think 'expanded memory' vs 'extended memory'...   ;-)
And boy, if you don't know what 'expanded memory' is (or was) it is because 
you are not *THAT* old!   ;-)
ET 

PS: And if you *REALLY* want convoluted memory management, think of 
segment-offset addressing and C compile time 'memory models':
http://80864beginner.com/Tutorial/Memory-Model.html
Yes, I am *THAT* old... 

Brian Weaver writes: 

> If you have more than 4GB of memory, you must use a 64bit kernel or the OS
> will not use the additional RAM over 4G. 
> 
>  
> 
> On Fri, May 31, 2013 at 10:00 AM, Nathan England <nathan at nmecs.com> wrote: 
> 
>> ** 
>>
>>
>> Keith, 
>>
>> 
>>
>> You and I have discussed this in the past. I have always been a proponent
>> of 32-bit over 64-bit because 32 is a little faster.If you have one or two
>> GB of ram, then that is true. But if the computer has more than 2 GB of ram
>> it will get some benefits of being 64-bit. But if your system has 4 GB or
>> more, you will likely notice a speed difference. About a year ago, when I
>> moved back to linux from windows, I went all 64-bit and I've not had any
>> troubles. 
>>
>> 
>>
>> You may not notice a difference, but your kernel will be happier. The are
>> three styles of kernels. 
>>
>> 
>>
>> (1) 32-bit kernels built for 1 or 2 GB of ram. These kernels do not have
>> PAE enabled and are very fast. (PAE = Physical Address Extensions) meaning
>> it allows to use more memory on a 32 bit system which really cannot use
>> that memory otherwise. It's like fake 64-bit. 
>>
>> 
>>
>> (2) 32-bit kernels built for more than 2 GB of ram. These kernels have PAE
>> enabled. I have read several articles now from people who have done tests,
>> as well as some reputable websites, that agree that PAE enabled kernels are
>> the slowest of the bunch. Addressing 64-bit memory space while operating in
>> a 32-bit environment takes a lot of tricks and creates some over-head. 
>>
>> 
>>
>> (3) 64-bit kernels are the fastest in all tests performed. These do not
>> play the PAE tricks as they are native and can address all memory space
>> properly. 
>>
>> 
>>
>> You as a user may not notice the difference in how any of the kernels
>> work, so it may be moot to you. But in the end, I would recommend you go
>> 64-bit anyway. 
>>
>> 
>>
>> Nathan 
>>
>> 
>>
>> On Friday, May 31, 2013 09:28:01 keith smith wrote: 
>>
>> 
>>
>>
>> Hi, 
>>
>> Even though I have 64bit hardware I always install the 32bit version of
>> Linux.  I do so because of the past discussions on this list that made me
>> believe the 32bit OS was better because 64bit caching is actually slower
>> due to the requirement that the cache be filled to a certain point before
>> it is moved.  I think I recall something about the amount of RAM having
>> some effect here also. 
>>
>> Using a 32bit version over a 64bit version seems counter intuitive,
>> however that is what I have taken away from these conversations about 32bit
>> vs 64bit Linux. 
>>
>> I'm using CentOS 6.x on a LAMP server that gets a low amount of traffic.
>> However I may make the jump to Linux on my desktop this summer. (this will
>> be my 3rd attempt to become M$ free except one VM so I can use IE for
>> testing) I think all of my hardware is 64bit. 
>>
>> So that begs the question, is 32bit better than 64bit or do I not
>> understand the issue? 
>>
>> Thank you for your feedback. 
>>
>> Keith 
>>
>> ------------------------
>> Keith Smith 
>>
>> 
>>
>> -- 
>>
>> 
>>
>> 
>>
>> 
>>
>> Regards, 
>>
>> 
>>
>> Nathan England 
>>
>> 
>>
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 
>>
>> NME Computer Services http://www.nmecs.com 
>>
>> Nathan England (nathan at nmecs.com) 
>>
>> Systems Administration / Web Application Development 
>>
>> Information Security Consulting 
>>
>> (480) 559.9681 
>>
>> 
>>
>> ---------------------------------------------------
>> PLUG-discuss mailing list - PLUG-discuss at lists.phxlinux.org
>> To subscribe, unsubscribe, or to change your mail settings:
>> http://lists.phxlinux.org/mailman/listinfo/plug-discuss 
>>