Re: shouldn't gcc use swap space as temp storage??

[Vladimir Murzin <murzin.v@gmail.com>]

On Thu, Sep 19, 2013 at 01:25:01AM +0100, Max B wrote:
> 
> 
> 
> 
> 
> 
> Hi All,
> 
> See below for executable program.
> 
> 
> Shouldn't gcc use swap space as temp storage?? Either my machine is set up improperly, or gcc does not (cannot?) access this capability.
> 
> 
> It seems to me that programs should be able to access swap memory in these cases, but the behaviour has not been confirmed.
> 
> Can someone please confirm or correct me?
> 

It is not because your machine settings or gcc. Your code is buggy.

> 
> Apologies if this is not the correct listserv for the present discussion.
> 

I think the proper list for C related questions is linux-c-programming or similar.

Vladimir

> 
> Thanks for any/all help.
> 
> 
> Cheers,
> Max
> 
> 
> /*
> ?* This program segfaults with the *bar array declaration.
> ?*
> ?* I wonder why it does not write the *foo array to swap space
> ?* then use the freed ram to allocate *bar.
> ?*
> ?* I have explored the shell ulimit parameters to no avail.
> ?*
> ?* I have run this as root and in userland with the same outcome.
> ?*
> ?* It seems to be a problem internal to gcc, but may also be a kernel issue.
> ?*
> ?*/
> 
> #include <stdio.h>
> #include <stdlib.h>
> 
> #define NMAX 628757505
> 
> int main(int argc,char **argv) {
> ? float *foo,*bar;
> 
> ? foo=calloc(NMAX,sizeof(float));
> ? fprintf(stderr,"%9.3f %9.3f\n",foo[0],foo[1]);
> #if 1
> ? bar=calloc(NMAX,sizeof(float));
> ? fprintf(stderr,"%9.3f %9.3f\n",bar[0],bar[1]);
> #endif
> 
> ? return
>  0;
> }

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