malloc on IRIX System V

David B. Anderson davea at quasar.wpd.sgi.com
Fri Jan 5 09:08:47 AEST 1990


In article <9001041731.AA03346 at acf8.NYU.EDU> kalvina at ACF8.NYU.EDU (Alan Kalvin) writes:
>
>If malloc is used to allocate an amount of memory greater or equal to
>the system page size, will the memory returned will be page-aligned?

No, not by default. And not with the libc.a malloc.

>If not, is it possible to force page-alignment?

Look at the mallinfo man page (M_GRAIN particularly).  Appropriately
configured and used, the malloc in libmalloc.a will do what you want.


Regards,
[ David B. Anderson  Silicon Graphics  (415)335-1548  davea at sgi.com ]

PS:
The traditional (before mallinfo()) way to do this is to 
a) malloc 1 page more than is needed.
b) adjust the returned pointer (upwards) to the nearest page boundary.
The extra space is ``wasted''.  Moreover, the adjusted pointer cannot
be used in a free(3) call (only the original pointer can be used with free() ).



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