Re: Address Space Limit - 2.25GB Per Process?
Re: Address Space Limit - 2.25GB Per Process?
- Subject: Re: Address Space Limit - 2.25GB Per Process?
- From: Paul Ripke <email@hidden>
- Date: Sat, 2 Nov 2002 00:05:07 +1100
On Thursday, October 31, 2002, at 09:22 PM, Jeremy T. Fox wrote:
I tried to find the most memory I could allocate via Fortran (g77) and
I got 2.25GB (on a G4 with 512MB of physical memory). Does Mac OS X
have a limit of 2.25GB per process, or is this something strange with
Fortran and/or my machine?
For comparison, Windows has a limit of 2GB per process (tunable to 3GB
if you shell out for Advanced Server), while I believe the default on
Linux is 3GB, which can be upgraded to 3.5GB with the right patch. I
don't know about FreeBSD. Clearly 64-bit machines do not have this
type of limitation.
Jeremy, who hopes that one day Apple will support 1GB DIMMs :)
If you're curious where everything gets mapped, try out vmmap(1). For
instance, on my machine, a process running a bash shell has the malloc
region starting at 0x8a000, dyld at 0x8fe00000, and the stack is at
0xbffff000.
Just doing the numbers on the contiguous malloc region says it's about
2.25 GB. Mind you, just mucking with a little bit of C code and vmmap,
malloc will allocate outside that region, provided you're not after
contiguous allocations. My routine stopped at a little under 3.5 GB.
Mind you, I didn't touch any of the pages...
Cheers,
--
Paul Ripke
Unix/OpenVMS/DBA
101 reasons why you can't find your Sysadmin:
67: It's 9AM and they're not working that late.
-- Koos van den Hout
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