ubuntu-mips team mailing list archive

[Michael Casadevall <sonicmctails@xxxxxxxxx>]

Very *very* few applications would use that much RAM. In those rare
cases, then yes, you need to compile for 64-bit, but I can't think of
anything in the stock Ubuntu archive that would use that much RAM by
default except maybe some database servers. Its a corner case however.

On 8/1/09, Kai-Cheung Leung <kcleung@xxxxxxxxxxxxxxxxxxxxx> wrote:
> However, will an user-space application that consume > 4GB memory be
> able to run on an OS with n32 userland and n64 kernel?
>
> Kaicheung
>
> On Sun, Aug 2, 2009 at 11:20 AM, Michael
> Casadevall<sonicmctails@xxxxxxxxx> wrote:
>> (apologizes in advance for not responding, I accidentally was not
>> subscribed to the list)
>>
>> An n64 userland is not desirable for a few reasons, the best setup
>> would be a n32 userland with n64 kernel, with specific optimizations
>> for anything that can truly benefit from the 64-bit userland. For the
>> vast majority of apps, 64-bits will not increase performance, and due
>> to the larger instruction size, reduce the amount of cache available,
>> actually degrading performance vs. a 32-bit userland. However, a
>> 64-bit kernel will allow a process to break the 4GiB memory barrier,
>> as well as allowing the userland to execute n64 applications.
>>
>> (w.r.t. to i386/x86_64, AMD added more registers when they revamped
>> the instruction set, from 4 to 16, hence why despite the above, there
>> is a general performance increase when going from 32-bit to 64-bit).
>> Michael
>>
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