ubuntu-mips team mailing list archive

[Kai-Cheung Leung <kcleung@xxxxxxxxxxxxxxxxxxxxx>]

However there are many applications , like what you said - database
servers, and an increasing number scientific modelling (such as
octave, scilab, matlab etc), datamining and bioinformatics
applications that can very easily take > 4GB!!!  And these
applications are the ones which are likely to run on clusters, or
GRID, of loongson multicore boxes.  Loongson is targetting very
heavily on these scientific / engineering markets.

Suppoose if the system has n64 kernel and it has both n32 and n64
glibc, then would it be possible for n32 and n64 applications to
co-exist?  In this case, applications that may need more than 4G can
compile with n64 and link to the n64 glibc (and other n64 libraries)
In this case, it would be difficult to maintain n32 and n64 versions
of *all* libraries in the repository!

If n32 and n64 cannot coexist easily, then perhaps we can make them
separately.  n32 for netbook and desktop, n64 for supercomputing.  As
they are for different markets.  However do you think we are asking
Canonical for too much to maintain both n32 and n64?

If you think the last option is feasible, then once the Chinese
students have made the Debian base port, we can immediately roll out
our Ubuntu n32 for the netbook / desktop market.

However to target the database server and supercomputing markets, we
still need to port Ubuntu to n64.

What do you guys think?

Kai-Cheung


On Sun, Aug 2, 2009 at 1:06 PM, Michael
Casadevall<sonicmctails@xxxxxxxxx> wrote:
> 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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>>
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>