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Re: large memory malloc
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Re: large memory malloc


  • Subject: Re: large memory malloc
  • From: "Justin C. Walker" <email@hidden>
  • Date: Thu, 30 Jun 2005 23:31:18 -0700


On Jun 30, 2005, at 17:47 , Mark Bessey wrote:

On Jun 30, 2005, at 5:32 PM, James E. Hopper wrote:


i have a simple xcode project that does a malloc that for the latest data set has grown to just under 3gb. the malloc is failing (on 10.3.9). since i have 4gb of ram and the docs imply i can access up to 4gb space without having to go to 64 bit addressing, i was hoping there was something simple i could do to make this work?


There probably isn't anything simple you can do to solve the problem without reworking your code, at least a little. While your process has a 4GB address space, there is bound to be some fragmentation of the available space, so the largest block you can allocate will always be somewhat smaller.

FWIW, the 4GB limit is what 32 bits buys you. Your process's address space comes with some pre-existing claims on some of that space:
- text (code)
- data
- stack
- shared libraries


The latter generally take a large chunk out of your space, and the stack's space is not insignificant. I don't believe that you can allocate memory in every corner of the "unclaimed" space in your address space, but I am not the expert here.

In short, you can't get more than about 3GB of memory allocated as you want it.

Regards,

Justin

--
Justin C. Walker, Curmudgeon-At-Large
Institute for General Semantics
--------
Some people have a mental horizon of radius zero, and
call it their point of view.
  -- David Hilbert
--------


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References: 
 >large memory malloc (From: "James E. Hopper" <email@hidden>)
 >Re: large memory malloc (From: Mark Bessey <email@hidden>)

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