Peter Tufvesson wrote:
> Hi all,
>
> I have now tried the program below on 2.2.12, 2.2.13, 2.3.36 (High memory
> support: Off, 4GB and 64GB) with the same result:
>
> My program can only allocate 910MB !!!
>
> What can be done about this? I need at least 2GB of virtual memory per
> process. I thought Linux could handle this?
>
> Thanks.
>
> -----------------------------------
>
> #include <string.h>
> #include <stdlib.h>
>
> main() {
> int i;
> void *x;
> x = (void *)4;
> for(i=0;x!=NULL;i++) {
> x = malloc(1024);
> if(x!=NULL) {
> memset(x,1024,6);
> if(i%1000)==0) {
> printf("malloc %d\n",i/1000);
> }
> }
> }
> sleep(20);
> }
>
> -
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> Please read the FAQ at http://www.tux.org/lkml/
You need to use mmap, malloc fails because it hits an address thats already
in use. The attached very hacky program mmap()s almost 3GB and tells
you which pages couldnt be allocated because there was already something
mapped there(like the text of this program itself).
Also, if you use memset your program will swap like crazy unless you have
3GB of physical memory...
Larry Woodman
http://www.missioncriticallinux.com
#include <string.h>
#include <stdlib.h>
#include <sys/mman.h>
main() {
int i;
void *x;
long siz=0;
long cantmap=0;
void *loc=0;
for(loc=0;loc<(void*)0xc0000000;loc+=0x1000) {
x = (void
*)mmap(loc,0x1000,PROT_READ|PROT_WRITE,MAP_ANONYMOUS|MAP_PRIVATE,-1,0);
if(x == (void*)-1) {
printf("size = %x, loc = %x, couldnt map = %x\n", siz, loc,
cantmap);
sleep(60);
} else {
siz+=0x1000;
if (x != loc) {
printf("mmap to %x returned %x\n",loc,x);
if (loc == 0) {
loc+=0x1000;
cantmap = 0x1000;
} else {
cantmap+=(abs(x-loc));
loc = x;
}
}
/* memset(x, 6, 0x1000); */
}
}
}
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