src/common/malloc.c

/* Copyright (c) 1990 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 * Fast malloc for memory hogs and VM environments.
 * Performs a minimum of searching through free lists.
 * malloc(), realloc() and free() use buckets
 *      containing blocks in powers of two, similar to CIT routines.
 * bfree() puts memory from any source into malloc free lists.
 * bmalloc() doesn't keep track of free lists -- it's usually
 *      just a buffered call to sbrk(2).  However, bmalloc will
 *      call mscrounge() if sbrk fails.
 * mscrounge() returns whatever free memory it can find to satisfy the
 *      request along with the number of bytes (modified).
 *
 *      Greg Ward       Lawrence Berkeley Laboratory
 */

#include  <errno.h>

#ifdef MSTATS
#include  <stdio.h>

static unsigned b_nalloced = 0;
static unsigned b_nfreed = 0;
static unsigned b_nscrounged = 0;
static unsigned m_nalloced = 0;
static unsigned m_nfreed = 0;
static unsigned m_nwasted = 0;
#else
#define  NULL           0
#endif

#ifndef ALIGN
#define  ALIGN          int                     /* align type */
#endif
#define  BYTES_WORD     sizeof(ALIGN)

#define  MAXINCR        (1<<16)                 /* largest sbrk(2) increment */

#ifdef  NOVMEM
#define  getpagesize()  BYTES_WORD
#endif
                                        /* malloc free lists */
typedef union m_head {
        union m_head    *next;
        int             bucket;
        ALIGN           dummy;
} M_HEAD;

#define FIRSTBUCKET     3
#define NBUCKETS        30

static M_HEAD   *free_list[NBUCKETS];


char *
mscrounge(np)           /* search free lists to satisfy request */
register unsigned       *np;
{
        char    *p;
        register int    bucket;
        register unsigned       bsiz;

        for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
                        bucket < NBUCKETS; bucket++, bsiz <<= 1)
                if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) {
                        *np = bsiz+sizeof(M_HEAD);
                        p = (char *)free_list[bucket];
                        free_list[bucket] = free_list[bucket]->next;
#ifdef MSTATS
                        b_nscrounged += *np;
#endif
                        return(p);
                }
        *np = 0;
        return(NULL);
}


char *
bmalloc(n)              /* allocate a block of n bytes, sans header */
register unsigned  n;
{
        extern char  *sbrk();
        static unsigned  pagesz = 0;
        static unsigned  amnt;
        static char  *bpos;
        static unsigned  nrem;
        unsigned  thisamnt;
        register char   *p;

#ifdef MSTATS
        b_nalloced += n;
#endif
        if (pagesz == 0) {                              /* initialize */
                pagesz = amnt = getpagesize();
                nrem = (int)sbrk(0);                    /* page align break */
                nrem = pagesz - (nrem&(pagesz-1));
                bpos = sbrk(nrem);                      /* word aligned! */
                if ((int)bpos == -1)
                        return(NULL);
        }

        n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1);         /* word align rqst. */

        if (n > nrem) {                                 /* need more core */
                if (n > amnt) {                         /* big chunk */
                        thisamnt = (n+(pagesz-1))&~(pagesz-1);
                        if (thisamnt <= MAXINCR)        /* increase amnt */
                                amnt = thisamnt;
                } else
                        thisamnt = amnt;
                p = sbrk(thisamnt);
                if ((int)p == -1) {                     /* uh-oh, ENOMEM */
                        thisamnt = n;                   /* search free lists */
                        p = mscrounge(&thisamnt);
                        if (p == NULL)                  /* we're really out */
                                return(NULL);
                }
                if (p != bpos+nrem) {                   /* not an increment */
                        bfree(bpos, nrem);              /* free what we have */
                        bpos = p;
                        nrem = thisamnt;
                } else                                  /* otherwise tack on */
                        nrem += thisamnt;
        }
        p = bpos;
        bpos += n;                                      /* advance */
        nrem -= n;
        return(p);
}


bfree(p, n)                     /* free n bytes of random memory */
register char  *p;
register unsigned  n;
{
        register int    bucket;
        register unsigned       bsiz;

#ifdef MSTATS
        b_nfreed += n;
#endif
                                        /* align pointer */
        bsiz = BYTES_WORD - ((unsigned)p&(BYTES_WORD-1));
        if (bsiz < BYTES_WORD) {
                p += bsiz;
                n -= bsiz;
        }
                                        /* fill big buckets first */
        for (bucket = NBUCKETS-1, bsiz = 1<<(NBUCKETS-1);
                        bucket >= FIRSTBUCKET; bucket--, bsiz >>= 1)
                if (n >= bsiz+sizeof(M_HEAD)) {
                        ((M_HEAD *)p)->next = free_list[bucket];
                        free_list[bucket] = (M_HEAD *)p;
                        p += bsiz+sizeof(M_HEAD);
                        n -= bsiz+sizeof(M_HEAD);
                }
}


char *
malloc(n)                       /* allocate n bytes of memory */
unsigned        n;
{
        extern int  errno;
        register M_HEAD *mp;
        register int    bucket;
        register unsigned       bsiz;
                                        /* find first bucket that fits */
        for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
                        bucket < NBUCKETS; bucket++, bsiz <<= 1)
                if (bsiz >= n)
                        break;
        if (bucket >= NBUCKETS) {
                errno = EINVAL;
                return(NULL);
        }
#ifdef MSTATS
        m_nalloced += bsiz + sizeof(M_HEAD);
        m_nwasted += bsiz + sizeof(M_HEAD) - n;
#endif
        if (free_list[bucket] == NULL) {        /* need more core */
                mp = (M_HEAD *)bmalloc(bsiz+sizeof(M_HEAD));
                if (mp == NULL)
                        return(NULL);
        } else {                                /* got it */
                mp = free_list[bucket];
                free_list[bucket] = mp->next;
        }
        mp->bucket = bucket;                    /* tag block */
        return((char *)(mp+1));
}


char *
realloc(op, n)                  /* reallocate memory using malloc() */
register char   *op;
unsigned        n;
{
        char    *p;
        register unsigned       on;
                                        /* get old size */
        if (op != NULL)
                on = 1 << ((M_HEAD *)op-1)->bucket;
        else
                on = 0;
        if (n <= on && (n > on>>1 || on == 1<<FIRSTBUCKET))
                return(op);             /* same bucket */
        p = malloc(n);
        if (p != NULL)
#ifdef  BSD
                bcopy(op, p, n>on ? on : n);
#else
                (void)memcpy(p, op, n>on ? on : n);
#endif
        free(op);
        return(p);
}


free(p)                 /* free memory allocated by malloc */
char    *p;
{
        register M_HEAD *mp;
        register int    bucket;

        if (p == NULL)
                return;
        mp = (M_HEAD *)p - 1;
        bucket = mp->bucket;
        mp->next = free_list[bucket];
        free_list[bucket] = mp;
#ifdef MSTATS
        m_nfreed += (1 << bucket) + sizeof(M_HEAD);
#endif
}


#ifndef NOVMEM
#ifndef BSD
#include <sys/var.h>
int
getpagesize()                   /* use SYSV var structure to get page size */
{
        struct var  v;

        uvar(&v);
        return(1 << v.v_pageshift);
}
#endif
#endif


#ifdef MSTATS
printmemstats(fp)               /* print memory statistics to stream */
FILE    *fp;
{
        register int    i;
        int     n;
        register M_HEAD *mp;
        unsigned int    total = 0;

        fprintf(fp, "Memory statistics:\n");
        fprintf(fp, "\tbmalloc: %d bytes allocated\n", b_nalloced);
        fprintf(fp, "\tbmalloc: %d bytes freed\n", b_nfreed);
        fprintf(fp, "\tbmalloc: %d bytes scrounged\n", b_nscrounged);
        fprintf(fp, "\tmalloc: %d bytes allocated\n", m_nalloced);
        fprintf(fp, "\tmalloc: %d bytes wasted (%.1f%%)\n", m_nwasted,
                        100.0*m_nwasted/m_nalloced);
        fprintf(fp, "\tmalloc: %d bytes freed\n", m_nfreed);
        for (i = NBUCKETS-1; i >= FIRSTBUCKET; i--) {
                n = 0;
                for (mp = free_list[i]; mp != NULL; mp = mp->next)
                        n++;
                if (n) {
                        fprintf(fp, "\t%d * %u\n", n, 1<<i);
                        total += n * ((1<<i) + sizeof(M_HEAD));
                }
        }
        fprintf(fp, "\t %u total bytes in free list\n", total);
}
#endif
Revision:	1.9
Committed:	Wed Oct 3 21:01:59 1990 UTC (33 years, 7 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.8:	+60 -1 lines
Log Message:	added memory statistics gathering (-DMSTATS)
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1990 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Fast malloc for memory hogs and VM environments.
9			* Performs a minimum of searching through free lists.
10	greg	1.4	* malloc(), realloc() and free() use buckets
11			* containing blocks in powers of two, similar to CIT routines.
12			* bfree() puts memory from any source into malloc free lists.
13			* bmalloc() doesn't keep track of free lists -- it's usually
14	greg	1.3	* just a buffered call to sbrk(2). However, bmalloc will
15			* call mscrounge() if sbrk fails.
16	greg	1.8	* mscrounge() returns whatever free memory it can find to satisfy the
17	greg	1.3	* request along with the number of bytes (modified).
18	greg	1.1	*
19			* Greg Ward Lawrence Berkeley Laboratory
20			*/
21
22	greg	1.6	#include <errno.h>
23
24	greg	1.9	#ifdef MSTATS
25			#include <stdio.h>
26
27			static unsigned b_nalloced = 0;
28			static unsigned b_nfreed = 0;
29			static unsigned b_nscrounged = 0;
30			static unsigned m_nalloced = 0;
31			static unsigned m_nfreed = 0;
32			static unsigned m_nwasted = 0;
33			#else
34	greg	1.1	#define NULL 0
35	greg	1.9	#endif
36	greg	1.1
37			#ifndef ALIGN
38			#define ALIGN int /* align type */
39			#endif
40			#define BYTES_WORD sizeof(ALIGN)
41
42	greg	1.9	#define MAXINCR (1<<16) /* largest sbrk(2) increment */
43	greg	1.3
44	greg	1.1	#ifdef NOVMEM
45			#define getpagesize() BYTES_WORD
46			#endif
47			/* malloc free lists */
48			typedef union m_head {
49			union m_head *next;
50			int bucket;
51			ALIGN dummy;
52			} M_HEAD;
53
54			#define FIRSTBUCKET 3
55			#define NBUCKETS 30
56
57			static M_HEAD *free_list[NBUCKETS];
58
59
60			char *
61	greg	1.4	mscrounge(np) /* search free lists to satisfy request */
62	greg	1.3	register unsigned *np;
63			{
64			char *p;
65			register int bucket;
66			register unsigned bsiz;
67
68			for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
69			bucket < NBUCKETS; bucket++, bsiz <<= 1)
70			if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) {
71			*np = bsiz+sizeof(M_HEAD);
72			p = (char *)free_list[bucket];
73			free_list[bucket] = free_list[bucket]->next;
74	greg	1.9	#ifdef MSTATS
75			b_nscrounged += *np;
76			#endif
77	greg	1.3	return(p);
78			}
79			*np = 0;
80			return(NULL);
81			}
82
83
84			char *
85	greg	1.1	bmalloc(n) /* allocate a block of n bytes, sans header */
86			register unsigned n;
87			{
88			extern char *sbrk();
89	greg	1.3	static unsigned pagesz = 0;
90			static unsigned amnt;
91	greg	1.1	static char *bpos;
92	greg	1.3	static unsigned nrem;
93			unsigned thisamnt;
94	greg	1.1	register char *p;
95
96	greg	1.9	#ifdef MSTATS
97			b_nalloced += n;
98			#endif
99	greg	1.1	if (pagesz == 0) { /* initialize */
100	greg	1.2	pagesz = amnt = getpagesize();
101	greg	1.1	nrem = (int)sbrk(0); /* page align break */
102			nrem = pagesz - (nrem&(pagesz-1));
103			bpos = sbrk(nrem); /* word aligned! */
104			if ((int)bpos == -1)
105			return(NULL);
106			}
107
108			n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align rqst. */
109
110			if (n > nrem) { /* need more core */
111	greg	1.3	if (n > amnt) { /* big chunk */
112			thisamnt = (n+(pagesz-1))&~(pagesz-1);
113			if (thisamnt <= MAXINCR) /* increase amnt */
114			amnt = thisamnt;
115			} else
116			thisamnt = amnt;
117			p = sbrk(thisamnt);
118	greg	1.4	if ((int)p == -1) { /* uh-oh, ENOMEM */
119	greg	1.3	thisamnt = n; /* search free lists */
120			p = mscrounge(&thisamnt);
121			if (p == NULL) /* we're really out */
122			return(NULL);
123			}
124			if (p != bpos+nrem) { /* not an increment */
125	greg	1.4	bfree(bpos, nrem); /* free what we have */
126	greg	1.1	bpos = p;
127	greg	1.3	nrem = thisamnt;
128	greg	1.4	} else /* otherwise tack on */
129	greg	1.3	nrem += thisamnt;
130	greg	1.1	}
131			p = bpos;
132			bpos += n; /* advance */
133			nrem -= n;
134			return(p);
135			}
136
137
138			bfree(p, n) /* free n bytes of random memory */
139	greg	1.2	register char *p;
140			register unsigned n;
141	greg	1.1	{
142			register int bucket;
143			register unsigned bsiz;
144	greg	1.9
145			#ifdef MSTATS
146			b_nfreed += n;
147			#endif
148	greg	1.4	/* align pointer */
149	greg	1.6	bsiz = BYTES_WORD - ((unsigned)p&(BYTES_WORD-1));
150	greg	1.4	if (bsiz < BYTES_WORD) {
151			p += bsiz;
152			n -= bsiz;
153	greg	1.1	}
154	greg	1.4	/* fill big buckets first */
155			for (bucket = NBUCKETS-1, bsiz = 1<<(NBUCKETS-1);
156			bucket >= FIRSTBUCKET; bucket--, bsiz >>= 1)
157			if (n >= bsiz+sizeof(M_HEAD)) {
158			((M_HEAD *)p)->next = free_list[bucket];
159			free_list[bucket] = (M_HEAD *)p;
160			p += bsiz+sizeof(M_HEAD);
161			n -= bsiz+sizeof(M_HEAD);
162			}
163	greg	1.1	}
164
165
166			char *
167			malloc(n) /* allocate n bytes of memory */
168			unsigned n;
169			{
170	greg	1.6	extern int errno;
171	greg	1.1	register M_HEAD *mp;
172			register int bucket;
173			register unsigned bsiz;
174	greg	1.2	/* find first bucket that fits */
175	greg	1.6	for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
176			bucket < NBUCKETS; bucket++, bsiz <<= 1)
177			if (bsiz >= n)
178			break;
179			if (bucket >= NBUCKETS) {
180			errno = EINVAL;
181			return(NULL);
182			}
183	greg	1.9	#ifdef MSTATS
184			m_nalloced += bsiz + sizeof(M_HEAD);
185			m_nwasted += bsiz + sizeof(M_HEAD) - n;
186			#endif
187	greg	1.4	if (free_list[bucket] == NULL) { /* need more core */
188	greg	1.1	mp = (M_HEAD *)bmalloc(bsiz+sizeof(M_HEAD));
189			if (mp == NULL)
190			return(NULL);
191	greg	1.4	} else { /* got it */
192	greg	1.1	mp = free_list[bucket];
193			free_list[bucket] = mp->next;
194			}
195	greg	1.4	mp->bucket = bucket; /* tag block */
196	greg	1.1	return((char *)(mp+1));
197			}
198
199
200			char *
201			realloc(op, n) /* reallocate memory using malloc() */
202	greg	1.6	register char *op;
203	greg	1.1	unsigned n;
204			{
205	greg	1.6	char *p;
206	greg	1.1	register unsigned on;
207	greg	1.6	/* get old size */
208	greg	1.5	if (op != NULL)
209			on = 1 << ((M_HEAD *)op-1)->bucket;
210			else
211			on = 0;
212	greg	1.6	if (n <= on && (n > on>>1 \|\| on == 1<<FIRSTBUCKET))
213	greg	1.5	return(op); /* same bucket */
214			p = malloc(n);
215			if (p != NULL)
216	greg	1.1	#ifdef BSD
217	greg	1.2	bcopy(op, p, n>on ? on : n);
218	greg	1.1	#else
219	greg	1.2	(void)memcpy(p, op, n>on ? on : n);
220	greg	1.1	#endif
221	greg	1.5	free(op);
222	greg	1.1	return(p);
223			}
224
225
226			free(p) /* free memory allocated by malloc */
227			char *p;
228			{
229			register M_HEAD *mp;
230			register int bucket;
231
232	greg	1.2	if (p == NULL)
233			return;
234	greg	1.1	mp = (M_HEAD *)p - 1;
235			bucket = mp->bucket;
236			mp->next = free_list[bucket];
237			free_list[bucket] = mp;
238	greg	1.9	#ifdef MSTATS
239			m_nfreed += (1 << bucket) + sizeof(M_HEAD);
240			#endif
241	greg	1.1	}
242
243
244			#ifndef NOVMEM
245			#ifndef BSD
246			#include <sys/var.h>
247			int
248			getpagesize() /* use SYSV var structure to get page size */
249			{
250			struct var v;
251
252	greg	1.8	uvar(&v);
253			return(1 << v.v_pageshift);
254	greg	1.1	}
255			#endif
256	greg	1.9	#endif
257
258
259			#ifdef MSTATS
260			printmemstats(fp) /* print memory statistics to stream */
261			FILE *fp;
262			{
263			register int i;
264			int n;
265			register M_HEAD *mp;
266			unsigned int total = 0;
267
268			fprintf(fp, "Memory statistics:\n");
269			fprintf(fp, "\tbmalloc: %d bytes allocated\n", b_nalloced);
270			fprintf(fp, "\tbmalloc: %d bytes freed\n", b_nfreed);
271			fprintf(fp, "\tbmalloc: %d bytes scrounged\n", b_nscrounged);
272			fprintf(fp, "\tmalloc: %d bytes allocated\n", m_nalloced);
273			fprintf(fp, "\tmalloc: %d bytes wasted (%.1f%%)\n", m_nwasted,
274			100.0*m_nwasted/m_nalloced);
275			fprintf(fp, "\tmalloc: %d bytes freed\n", m_nfreed);
276			for (i = NBUCKETS-1; i >= FIRSTBUCKET; i--) {
277			n = 0;
278			for (mp = free_list[i]; mp != NULL; mp = mp->next)
279			n++;
280			if (n) {
281			fprintf(fp, "\t%d * %u\n", n, 1<<i);
282			total += n * ((1<<i) + sizeof(M_HEAD));
283			}
284			}
285			fprintf(fp, "\t %u total bytes in free list\n", total);
286			}
287	greg	1.1	#endif