Re: Is there a 1GB memory ceiling for vm_allocate?
Re: Is there a 1GB memory ceiling for vm_allocate?
- Subject: Re: Is there a 1GB memory ceiling for vm_allocate?
- From: Steve Checkoway <email@hidden>
- Date: Tue, 23 Jan 2007 23:34:02 -0800
On Jan 23, 2007, at 8:48 PM, Robert Purves wrote:
Roughly 3.5 GB of the theoretical 4 GB address space is available
for allocation by an app. However you can't get all that in one
chunk; it's already fragmented by the time the app starts.
Typically the largest successful block request is about 1.5 GB.
For the record, the largest I can allocate in one chunk using malloc
at the beginning of my program is 0x8CDF8000 bytes. I wrote a program
to see just how much I could allocate in total and I was able to malloc
0x8CDF8000
0x3FFEC000
0x0F800000
0x007F8000
0x007F8000
0x0018D000
0x000FB000
0x000FB000
0x000FA000
0x00008000
0x00003BFF 0x222 times
0x000001F0 0x841 times
0x000000E0
0x00000010 0x2 times.
Increasing any of those numbers by one would fail. Unless I made a
mistake adding this up, that gives 3,728,049,358 bytes or 3.4 GB.
I still have the code if anyone would like to see it (though I can't
imagine why anyone would).
--
Steve Checkoway
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