Looks are deceiving, the addr is a mmap() address, rather than from a traditional
malloc pool. I think anything over 128k is mmapped, so that it can be unmapped
without the fragmenting the malloc pool with large memory holes
/gat
btw by printing in hex u may see the allocation better.
btw#2 malloc allocation is on a per 'C' library basis. I dont know if ccc (
true64 c compiler ) uses glibc or their own.
"T. Daniel Crawford" wrote:
> Hi, all,
>
> I'm having trouble with the way the memory allocation system works in C
> as implemented under alpha Linux. Here's some simple code:
>
> ------------------------------------------------------------------------------
> #include <stdio.h>
> #include <stdlib.h>
>
> int main(void)
> {
> long int *n, size;
>
> printf("%d %d %d\n", sizeof(int), sizeof(long int), sizeof(long long
> int));
>
> size = 1;
> n = (long int *) malloc(size * sizeof(int));
> printf("size = %d; n = %ld\n", size, n);
>
> size = 1000;
> n = (long int *) malloc(size * sizeof(int));
> printf("size = %d; n = %ld\n", size, n);
>
> size = 100000;
> n = (long int *) malloc(size * sizeof(int));
> printf("size = %d; n = %ld\n", size, n);
>
> return 0;
> }
> ------------------------------------------------------------------------------
>
> The output from this program using the Compaq C compiler, ccc, is:
>
> 4 8 8
> size = 1; n = 4832890112
> size = 1000; n = 4832890608
> size = 100000; n = 2199023427600
>
> Note that I get nearly the same results using GNU C.
>
> Now, if, instead, I run this under Compaq's Tru64 UNIX, I get:
>
> 4 8 8
> size = 1; n = 5368717568
> size = 1000; n = 5368721408
> size = 100000; n = 5368765536
>
> For the large-block allocation, on alpha Linux the address is off in the
> middle of nowhere (from my perspective) while on alpha Tru64 both the small-
> and large-block allocations end up in approximately the same region of
> address space.
>
> My questions: (1) I am misinterpreting my results? (2) If not, why does
> this happen?
>
> Thanks in advance for any help!
>
> -Daniel
>
> --
> T. Daniel Crawford Department of Chemistry
> crawdad@vt.edu Virginia Tech
> www.chem.vt.edu/chem-dept/crawford Voice: 540-231-7760 FAX: 540-231-3255
>
> _______________________________________________
> Axp-list mailing list
> Axp-list@redhat.com
> https://listman.redhat.com/mailman/listinfo/axp-list
_______________________________________________
Axp-list mailing list
Axp-list@redhat.com
https://listman.redhat.com/mailman/listinfo/axp-list
This archive was generated by hypermail version 2a22 on Sat Mar 3 12:54:54 2001 PST
Send any problems or questions about this archive to webmaster@alphalinux.org.