PC RAM and process address space

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Suppose I have 3 gb of ram and 250 gb hard disk in my pc.
Now I wrote a simple C program having only one statement malloc() to allocate 4 gb of memory as 32 bit os can address 4gb address space then will the malloc succeed?
If yes then how it will get extra 1 gb of memory?
Does the process gets memory only from RAM or also from harddisk?

Posted 29-Nov-11 23:59pm

rupeshkp728

Updated 30-Nov-11 0:00am

v2

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elgaabeb · Answer 1 · 2011-11-30T00:12:00

Solution 1

Hi,

When the requested memory is higher than RAM size, The OS uses virtual memory technique.
take a look at this artical:
Virtual_memory[^]

Best regards.
EL GAABEB.

Posted 30-Nov-11 0:12am

elgaabeb

Updated 30-Nov-11 0:13am

v2

CPallini · Answer 2 · 2011-11-30T00:16:00

Solution 2

Usually heap size is lower than 4 Gb, see, for instance "Why can't I get a larger heap with the 32-bit JVM?"[^].
The process gets virtual memory that is partly mapped on the hard-disk, see "How Virtual Memory Works"[^].

Posted 30-Nov-11 0:16am

CPallini

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rupeshkp728 1-Dec-11 2:50am

Thanks pallini for the link.

CPallini 1-Dec-11 4:21am

You are welcome.