dmd platform support - poll

BCS ao at
Sat Dec 27 18:41:29 PST 2008

Reply to Andrei,

> BCS wrote:
>> Reply to Andrei,
>>> In my opinion, it's not application pressure that drives 64-bit
>>> machine adoption, now or in the near future. It's RAM price,
>>> availability, and usefulness. A 32-bit machine cannot gainfully have
>>> more than 4GB of RAM, period.
>> IIRC 32 bit Intel chips can address more like 64GB of RAM (I can't
>> find
>> the ref but I seem to recall about 4 extra address bits). It's just
>> virtual address spaces that are limited to 4GB (or 2-3GB after the OS
>> takes it's pound of flesh)
>> As pointed out, only a few apps need anything near 2GB of RAM per
>> process.

found a ref:

the CPU limit has to be >=128GB (look at Server 2003) or it might be 64GB 
(re linux)

> Even if only a few apps need anything near 2GB of RAM per process,
> their sum will exceed that limit rather quickly, which gives strong
> justification to 64-bit OSs. (Not sure if you meant to basically say
> the same.)

Most people will not have problems with 2GB/process limits, those that do 
can go 64bit. Most people won't have much use for more than about 8-16GB 
total of RAM and those are well within the CPU's limit (but outside the OS's 

My point is that few people are pushing either the per process or system 
total memory limits of the x86-32bit CPUs and need something that only 64bit 
CPU's will give them. (OTOH you might need 64bit to run the OS you need to 
get at enough RAM)

> The real problem is that there are applications that need as much
> memory as they could possibly get, and for those dmd simply offers no
> option.

Agree. Compilers seem to need to be written for the corner cases. "No one 
will ever need to do that" is never a valid answer.

> Andrei

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