Interrogating the Memory System

Memory System Calls

Memory Information	System Call Invocation
Size of a page	uiPageSize = getpagesize(); ulPageSize = sysconf(_SC_PAGESIZE);
Virtual and resident sizes of a process	syssgi(SGI_PROCSZ, pid, &uiSZ, &uiRSS);
Maximum stack size of a process	uiStackSize = prctl(PR_GETSTACKSIZE)
Free swap space in 512-byte units	swapctl(SC_GETFREESWAP, &uiBlocks);
Total physical swap space in 512-byte units	swapctl(SC_GETSWAPTOT, &uiBlocks);
Total real memory	sysmp(MP_KERNADDR, MPSA_RMINFO, &rmstruct);
Free real memory	sysmp(MP_KERNADDR, MPSA_RMINFO, &rmstruct);
Total real memory + swap space	sysmp(MP_KERNADDR, MPSA_RMINFO, &rmstruct);

The structure used with the sysmp() call shown above has this form (a more detailed layout is in sys/sysmp.h):

struct rminfo {
   long freemem; /* pages of free memory */
   long availsmem; /* total real+swap memory space */
   long availrmem; /* available real memory space */
   long bufmem; /* not useful */
   long physmem; /* total real memory space */
};