xref: /original-bsd/sys/vax/include/vmparam.h (revision bbb96de4)
1 /*
2  * Copyright (c) 1982, 1986 Regents of the University of California.
3  * All rights reserved.  The Berkeley software License Agreement
4  * specifies the terms and conditions for redistribution.
5  *
6  *	@(#)vmparam.h	7.3 (Berkeley) 05/10/90
7  */
8 
9 /*
10  * Machine dependent constants for VAX
11  */
12 /*
13  * USRTEXT is the start of the user text/data space, while USRSTACK
14  * is the top (end) of the user stack.  LOWPAGES and HIGHPAGES are
15  * the number of pages from the beginning of the P0 region to the
16  * beginning of the text and from the beginning of the P1 region to the
17  * beginning of the stack respectively.
18  */
19 #define	USRTEXT		0
20 #define	USRSTACK	(0x80000000-UPAGES*NBPG) /* Start of user stack */
21 #define	BTOPUSRSTACK	(0x400000 - UPAGES)	 /* btop(USRSTACK) */
22 /* number of ptes per page */
23 #define	P1PAGES		0x200000	/* number of pages in P1 region */
24 #define	LOWPAGES	0
25 #define	HIGHPAGES	UPAGES
26 
27 /*
28  * Virtual memory related constants, all in bytes
29  */
30 #ifndef MAXTSIZ
31 #define	MAXTSIZ		(6*1024*1024)		/* max text size */
32 #endif
33 #ifndef DFLDSIZ
34 #define	DFLDSIZ		(6*1024*1024)		/* initial data size limit */
35 #endif
36 #ifndef MAXDSIZ
37 #define	MAXDSIZ		(16*1024*1024)		/* max data size */
38 #endif
39 #ifndef	DFLSSIZ
40 #define	DFLSSIZ		(512*1024)		/* initial stack size limit */
41 #endif
42 #ifndef	MAXSSIZ
43 #define	MAXSSIZ		MAXDSIZ			/* max stack size */
44 #endif
45 
46 /*
47  * Default sizes of swap allocation chunks (see dmap.h).
48  * The actual values may be changed in vminit() based on MAXDSIZ.
49  * With MAXDSIZ of 16Mb and NDMAP of 38, dmmax will be 1024.
50  * DMMIN should be at least ctod(1) so that vtod() works.
51  * vminit() ensures this.
52  */
53 #define	DMMIN	32			/* smallest swap allocation */
54 #define	DMMAX	4096			/* largest potential swap allocation */
55 #define	DMTEXT	1024			/* swap allocation for text */
56 
57 /*
58  * Sizes of the system and user portions of the system page table.
59  */
60 /* SYSPTSIZE IS SILLY; IT SHOULD BE COMPUTED AT BOOT TIME */
61 #define	SYSPTSIZE	((20+MAXUSERS)*NPTEPG)
62 #define	USRPTSIZE 	(32*NPTEPG)
63 
64 /*
65  * PTEs for system V compatible shared memory.
66  * This is basically slop for kmempt which we actually allocate (malloc) from.
67  */
68 #define SHMMAXPGS	1024
69 
70 /*
71  * Boundary at which to place first MAPMEM segment if not explicitly
72  * specified.  Should be a power of two.  This allows some slop for
73  * the data segment to grow underneath the first mapped segment.
74  */
75 #define MMSEG		0x200000
76 
77 /*
78  * The size of the clock loop.
79  */
80 #define	LOOPPAGES	(maxfree - firstfree)
81 
82 /*
83  * The time for a process to be blocked before being very swappable.
84  * This is a number of seconds which the system takes as being a non-trivial
85  * amount of real time.  You probably shouldn't change this;
86  * it is used in subtle ways (fractions and multiples of it are, that is, like
87  * half of a ``long time'', almost a long time, etc.)
88  * It is related to human patience and other factors which don't really
89  * change over time.
90  */
91 #define	MAXSLP 		20
92 
93 /*
94  * A swapped in process is given a small amount of core without being bothered
95  * by the page replacement algorithm.  Basically this says that if you are
96  * swapped in you deserve some resources.  We protect the last SAFERSS
97  * pages against paging and will just swap you out rather than paging you.
98  * Note that each process has at least UPAGES+CLSIZE pages which are not
99  * paged anyways (this is currently 8+2=10 pages or 5k bytes), so this
100  * number just means a swapped in process is given around 25k bytes.
101  * Just for fun: current memory prices are 4600$ a megabyte on VAX (4/22/81),
102  * so we loan each swapped in process memory worth 100$, or just admit
103  * that we don't consider it worthwhile and swap it out to disk which costs
104  * $30/mb or about $0.75.
105  */
106 #define	SAFERSS		32		/* nominal ``small'' resident set size
107 					   protected against replacement */
108 
109 /*
110  * DISKRPM is used to estimate the number of paging i/o operations
111  * which one can expect from a single disk controller.
112  */
113 #define	DISKRPM		60
114 
115 /*
116  * Klustering constants.  Klustering is the gathering
117  * of pages together for pagein/pageout, while clustering
118  * is the treatment of hardware page size as though it were
119  * larger than it really is.
120  *
121  * KLMAX gives maximum cluster size in CLSIZE page (cluster-page)
122  * units.  Note that ctod(KLMAX*CLSIZE) must be <= DMMIN in dmap.h.
123  * ctob(KLMAX) should also be less than MAXPHYS (in vm_swp.c) to
124  * avoid "big push" panics.
125  */
126 
127 #define	KLMAX	(32/CLSIZE)
128 #define	KLSEQL	(16/CLSIZE)		/* in klust if vadvise(VA_SEQL) */
129 #define	KLIN	(8/CLSIZE)		/* default data/stack in klust */
130 #define	KLTXT	(4/CLSIZE)		/* default text in klust */
131 #define	KLOUT	(32/CLSIZE)
132 
133 /*
134  * KLSDIST is the advance or retard of the fifo reclaim for sequential
135  * processes data space.
136  */
137 #define	KLSDIST	3		/* klusters advance/retard for seq. fifo */
138 
139 /*
140  * Paging thresholds (see vm_sched.c).
141  * Strategy of 1/19/85:
142  *	lotsfree is 512k bytes, but at most 1/4 of memory
143  *	desfree is 200k bytes, but at most 1/8 of memory
144  *	minfree is 64k bytes, but at most 1/2 of desfree
145  */
146 #define	LOTSFREE	(512 * 1024)
147 #define	LOTSFREEFRACT	4
148 #define	DESFREE		(200 * 1024)
149 #define	DESFREEFRACT	8
150 #define	MINFREE		(64 * 1024)
151 #define	MINFREEFRACT	2
152 
153 /*
154  * There are two clock hands, initially separated by HANDSPREAD bytes
155  * (but at most all of user memory).  The amount of time to reclaim
156  * a page once the pageout process examines it increases with this
157  * distance and decreases as the scan rate rises.
158  */
159 #define	HANDSPREAD	(2 * 1024 * 1024)
160 
161 /*
162  * The number of times per second to recompute the desired paging rate
163  * and poke the pagedaemon.
164  */
165 #define	RATETOSCHEDPAGING	4
166 
167 /*
168  * Believed threshold (in megabytes) for which interleaved
169  * swapping area is desirable.
170  */
171 #define	LOTSOFMEM	2
172 
173 #define	mapin(pte, v, pfnum, prot) \
174 	(*(int *)(pte) = (pfnum) | (prot), mtpr(TBIS, v))
175