Messages in this thread | | | Date | Tue, 29 Jul 2003 10:32:41 +0530 (IST) | From | Nagendra Singh Tomar <> | Subject | Re: malloc problem to allocate very large blocks |
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I missed the system details, you already have >2GB virtual memory.
--tomar On Tue, 29 Jul 2003, Tomar, Nagendra wrote:
> AFAIK malloc will not return you memory more than the total virtual > memory > (RAM+swap) in the system. So if you want more than 2GB allocations from > malloc, make sure you have at least 2GB virtual mem, keeping aside some > space for the kernel. > > --tomar > > On Mon, 28 Jul 2003, Tung-Han Hsieh wrote: > > > Hello, > > > > I am developing applications which requires more than 2GB memory. > > But I found that in my Linux system the malloc() cannot allocate > > more than 2GB memory. Here is the details of my system: > > > > CPU: Pentium 4 2.53 GHz > > RAM: 2 GB > > Swap: 512 MB > > OS: Debian-3.0 stable > > Kernel: 2.4.20 > > gcc: 2.95.4 20011002 > > glibc: 2.2.5-6 > > > > In theory, in a 32-bits machine the maximum allocatable memory > > is up to 4GB. But in the following very simple testing program: > > > > ===================================================================== > > #include <stdio.h> > > #include <stdlib.h> > > > > main() > > { > > size_t l; > > char *s1=NULL, *s2=NULL; > > > > l = 1024*1024*1024; > > > > s1 = malloc(l); > > s2 = malloc(l); > > if (! s1) printf("s1 malloc failed\n"); > > if (! s2) printf("s2 malloc failed\n"); > > } > > ===================================================================== > > > > only the block for s1 can be allocated. Further, if I change the > > program to > > > > ===================================================================== > > #include <stdio.h> > > #include <stdlib.h> > > > > main() > > { > > size_t l; > > char *s1=NULL; > > > > l = 2*1024*1024*1024; > > > > s1 = malloc(l); > > if (! s1) printf("s1 malloc failed\n"); > > } > > ===================================================================== > > > > the gcc complier complain to me that "foo.c:9: warning: integer > overflow > > in expression" during the compilation (I use: "gcc foo.c" to compile > > it), > > and the block for s1 cannot be allocated at all. I am wondering if > there > > is any way to overcome the 2GB limit. > > > > Thank you very much for your reply in advance. > > > > > > Best Regards, > > > > T.H.Hsieh > > - > > To unsubscribe from this list: send the line "unsubscribe > linux-kernel" > > in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" > in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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