a/sys/vax/vmparam.h

/*      vmparam.h       4.2     82/11/13        */

/*
 * Machine dependent constants for VAX
 */
/*
 * USRTEXT is the start of the user text/data space, while USRSTACK
 * is the top (end) of the user stack.  LOWPAGES and HIGHPAGES are
 * the number of pages from the beginning of the P0 region to the
 * beginning of the text and from the beginning of the P1 region to the
 * beginning of the stack respectively.
 */
                                        /* number of ptes per page */
#define USRTEXT         0
#define USRSTACK        (0x80000000-UPAGES*NBPG)
                                        /* Start of user stack */
#define P1PAGES         0x200000        /* number of pages in P1 region */
#define LOWPAGES        0
#define HIGHPAGES       UPAGES

/*
 * Virtual memory related constants
 */
#define SLOP    32
#define MAXTSIZ         (6*2048-SLOP)           /* max text size (clicks) */
#ifndef MAXDSIZ
#define MAXDSIZ         (12*1024-32-SLOP)       /* max data size (clicks) */
#endif
#define MAXSSIZ         (12*1024-32-SLOP)       /* max stack size (clicks) */

/*
 * Sizes of the system and user portions of the system page table.
 */
/* SYSPTSIZE IS SILLY; IT SHOULD BE COMPUTED AT BOOT TIME */
#define SYSPTSIZE       (35*NPTEPG)
#define USRPTSIZE       (8*NPTEPG)

/*
 * The size of the clock loop.
 */
#define LOOPPAGES       (maxfree - firstfree)

/*
 * The time for a process to be blocked before being very swappable.
 * This is a number of seconds which the system takes as being a non-trivial
 * amount of real time.  You probably shouldn't change this;
 * it is used in subtle ways (fractions and multiples of it are, that is, like
 * half of a ``long time'', almost a long time, etc.)
 * It is related to human patience and other factors which don't really
 * change over time.
 */
#define MAXSLP          20

/*
 * A swapped in process is given a small amount of core without being bothered
 * by the page replacement algorithm.  Basically this says that if you are
 * swapped in you deserve some resources.  We protect the last SAFERSS
 * pages against paging and will just swap you out rather than paging you.
 * Note that each process has at least UPAGES+CLSIZE pages which are not
 * paged anyways (this is currently 8+2=10 pages or 5k bytes), so this
 * number just means a swapped in process is given around 25k bytes.
 * Just for fun: current memory prices are 4600$ a megabyte on VAX (4/22/81),
 * so we loan each swapped in process memory worth 100$, or just admit
 * that we don't consider it worthwhile and swap it out to disk which costs
 * $30/mb or about $0.75.
 */
#define SAFERSS         32              /* nominal ``small'' resident set size
                                           protected against replacement */

/*
 * DISKRPM is used to estimate the number of paging i/o operations
 * which one can expect from a single disk controller.
 */
#define DISKRPM         60

/*
 * Klustering constants.  Klustering is the gathering
 * of pages together for pagein/pageout, while clustering
 * is the treatment of hardware page size as though it were
 * larger than it really is.
 *
 * KLMAX gives maximum cluster size in CLSIZE page (cluster-page)
 * units.  Note that KLMAX*CLSIZE must be <= DMMIN in dmap.h.
 */

#define KLMAX   (32/CLSIZE)
#define KLSEQL  (16/CLSIZE)             /* in klust if vadvise(VA_SEQL) */
#define KLIN    (8/CLSIZE)              /* default data/stack in klust */
#define KLTXT   (4/CLSIZE)              /* default text in klust */
#define KLOUT   (32/CLSIZE)

/*
 * KLSDIST is the advance or retard of the fifo reclaim for sequential
 * processes data space.
 */
#define KLSDIST 3               /* klusters advance/retard for seq. fifo */