I had a private note from Mike Harris following my previous post in this
thread. Mike noted the Compaq/DEC Alpha architecture uses 8K pages. He
didn't say whether this is true for all OSes; as he also noted, the x86
architecture - in more recent generations - supports large 4M pages as well
as the more commonly used 4K ones. (There was an excellent article in _Dr.
Dobb's Journal_ some months back on using large x86 pages.)
After reading his note I realized I should probably have mentioned that
SUSv2-compliant[1] OSes generally will tell you the page size using sysconf:
----- cut here -----
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main(void)
{
long PageSize;
/* Get page size in bytes */
PageSize = sysconf(_SC_PAGESIZE);
if (PageSize < 0)
{
/* sysconf doesn't set errno, so perror isn't useful here */
fputs("error in sysconf\n", stderr);
return EXIT_FAILURE;
}
else if (PageSize == 0)
{
/* sysconf doesn't set errno, so perror isn't useful here */
fputs("page size is unknown\n", stderr);
return EXIT_FAILURE;
}
else
{
printf("page size in bytes: %ld\n", PageSize);
}
return EXIT_SUCCESS;
}
----- cut here -----
Many Unixish OSes also provide a "pagesize" command which prints the page
size in bytes, and a getpagesize() function which is equivalent to
sysconf(_SC_PAGESIZE). They apparently originated in BSD4.2 and were picked
up in SVR4.
Note, though, in the context of this thread, that the page size is not
likely to be a terribly useful piece of information.
[1] "SUSv2" is the Single Unix Specification version 2. sysconf is a POSIX
function, but _SC_PAGESIZE is not part of POSIX.2 AFAIK.
Michael Wojcik michael.wojcikat_private
MERANT
Department of English, Miami University
This archive was generated by hypermail 2b30 : Mon Jul 02 2001 - 18:18:48 PDT