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];

static char     DUMMYLOC[BYTES_WORD];


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;
                                        /* don't return NULL on 0 request */
        if (n == 0)
                return(DUMMYLOC);
                                        /* 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 && op != DUMMYLOC)
                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 || p == DUMMYLOC)
                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:	1.10
Committed:	Tue Nov 13 14:39:05 1990 UTC (33 years, 5 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.9:	+7 -3 lines
Log Message:	added check for zero request
#	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			static unsigned b_nalloced = 0;
27			static unsigned b_nfreed = 0;
28			static unsigned b_nscrounged = 0;
29			static unsigned m_nalloced = 0;
30			static unsigned m_nfreed = 0;
31			static unsigned m_nwasted = 0;
32			#else
33	greg	1.1	#define NULL 0
34	greg	1.9	#endif
35	greg	1.1
36			#ifndef ALIGN
37			#define ALIGN int /* align type */
38			#endif
39			#define BYTES_WORD sizeof(ALIGN)
40
41	greg	1.9	#define MAXINCR (1<<16) /* largest sbrk(2) increment */
42	greg	1.3
43	greg	1.1	#ifdef NOVMEM
44			#define getpagesize() BYTES_WORD
45			#endif
46			/* malloc free lists */
47			typedef union m_head {
48			union m_head *next;
49			int bucket;
50			ALIGN dummy;
51			} M_HEAD;
52
53			#define FIRSTBUCKET 3
54			#define NBUCKETS 30
55
56			static M_HEAD *free_list[NBUCKETS];
57
58	greg	1.10	static char DUMMYLOC[BYTES_WORD];
59	greg	1.1
60	greg	1.10
61	greg	1.1	char *
62	greg	1.4	mscrounge(np) /* search free lists to satisfy request */
63	greg	1.3	register unsigned *np;
64			{
65			char *p;
66			register int bucket;
67			register unsigned bsiz;
68
69			for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
70			bucket < NBUCKETS; bucket++, bsiz <<= 1)
71			if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) {
72			*np = bsiz+sizeof(M_HEAD);
73			p = (char *)free_list[bucket];
74			free_list[bucket] = free_list[bucket]->next;
75	greg	1.9	#ifdef MSTATS
76			b_nscrounged += *np;
77			#endif
78	greg	1.3	return(p);
79			}
80			*np = 0;
81			return(NULL);
82			}
83
84
85			char *
86	greg	1.1	bmalloc(n) /* allocate a block of n bytes, sans header */
87			register unsigned n;
88			{
89			extern char *sbrk();
90	greg	1.3	static unsigned pagesz = 0;
91			static unsigned amnt;
92	greg	1.1	static char *bpos;
93	greg	1.3	static unsigned nrem;
94			unsigned thisamnt;
95	greg	1.1	register char *p;
96
97	greg	1.9	#ifdef MSTATS
98			b_nalloced += n;
99			#endif
100	greg	1.1	if (pagesz == 0) { /* initialize */
101	greg	1.2	pagesz = amnt = getpagesize();
102	greg	1.1	nrem = (int)sbrk(0); /* page align break */
103			nrem = pagesz - (nrem&(pagesz-1));
104			bpos = sbrk(nrem); /* word aligned! */
105			if ((int)bpos == -1)
106			return(NULL);
107			}
108
109			n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align rqst. */
110
111			if (n > nrem) { /* need more core */
112	greg	1.3	if (n > amnt) { /* big chunk */
113			thisamnt = (n+(pagesz-1))&~(pagesz-1);
114			if (thisamnt <= MAXINCR) /* increase amnt */
115			amnt = thisamnt;
116			} else
117			thisamnt = amnt;
118			p = sbrk(thisamnt);
119	greg	1.4	if ((int)p == -1) { /* uh-oh, ENOMEM */
120	greg	1.3	thisamnt = n; /* search free lists */
121			p = mscrounge(&thisamnt);
122			if (p == NULL) /* we're really out */
123			return(NULL);
124			}
125			if (p != bpos+nrem) { /* not an increment */
126	greg	1.4	bfree(bpos, nrem); /* free what we have */
127	greg	1.1	bpos = p;
128	greg	1.3	nrem = thisamnt;
129	greg	1.4	} else /* otherwise tack on */
130	greg	1.3	nrem += thisamnt;
131	greg	1.1	}
132			p = bpos;
133			bpos += n; /* advance */
134			nrem -= n;
135			return(p);
136			}
137
138
139			bfree(p, n) /* free n bytes of random memory */
140	greg	1.2	register char *p;
141			register unsigned n;
142	greg	1.1	{
143			register int bucket;
144			register unsigned bsiz;
145	greg	1.9
146			#ifdef MSTATS
147			b_nfreed += n;
148			#endif
149	greg	1.4	/* align pointer */
150	greg	1.6	bsiz = BYTES_WORD - ((unsigned)p&(BYTES_WORD-1));
151	greg	1.4	if (bsiz < BYTES_WORD) {
152			p += bsiz;
153			n -= bsiz;
154	greg	1.1	}
155	greg	1.4	/* fill big buckets first */
156			for (bucket = NBUCKETS-1, bsiz = 1<<(NBUCKETS-1);
157			bucket >= FIRSTBUCKET; bucket--, bsiz >>= 1)
158			if (n >= bsiz+sizeof(M_HEAD)) {
159			((M_HEAD *)p)->next = free_list[bucket];
160			free_list[bucket] = (M_HEAD *)p;
161			p += bsiz+sizeof(M_HEAD);
162			n -= bsiz+sizeof(M_HEAD);
163			}
164	greg	1.1	}
165
166
167			char *
168			malloc(n) /* allocate n bytes of memory */
169			unsigned n;
170			{
171	greg	1.6	extern int errno;
172	greg	1.1	register M_HEAD *mp;
173			register int bucket;
174			register unsigned bsiz;
175	greg	1.10	/* don't return NULL on 0 request */
176			if (n == 0)
177			return(DUMMYLOC);
178	greg	1.2	/* find first bucket that fits */
179	greg	1.6	for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
180			bucket < NBUCKETS; bucket++, bsiz <<= 1)
181			if (bsiz >= n)
182			break;
183			if (bucket >= NBUCKETS) {
184			errno = EINVAL;
185			return(NULL);
186			}
187	greg	1.9	#ifdef MSTATS
188			m_nalloced += bsiz + sizeof(M_HEAD);
189			m_nwasted += bsiz + sizeof(M_HEAD) - n;
190			#endif
191	greg	1.4	if (free_list[bucket] == NULL) { /* need more core */
192	greg	1.1	mp = (M_HEAD *)bmalloc(bsiz+sizeof(M_HEAD));
193			if (mp == NULL)
194			return(NULL);
195	greg	1.4	} else { /* got it */
196	greg	1.1	mp = free_list[bucket];
197			free_list[bucket] = mp->next;
198			}
199	greg	1.4	mp->bucket = bucket; /* tag block */
200	greg	1.1	return((char *)(mp+1));
201			}
202
203
204			char *
205			realloc(op, n) /* reallocate memory using malloc() */
206	greg	1.6	register char *op;
207	greg	1.1	unsigned n;
208			{
209	greg	1.6	char *p;
210	greg	1.1	register unsigned on;
211	greg	1.6	/* get old size */
212	greg	1.10	if (op != NULL && op != DUMMYLOC)
213	greg	1.5	on = 1 << ((M_HEAD *)op-1)->bucket;
214			else
215			on = 0;
216	greg	1.6	if (n <= on && (n > on>>1 \|\| on == 1<<FIRSTBUCKET))
217	greg	1.5	return(op); /* same bucket */
218			p = malloc(n);
219			if (p != NULL)
220	greg	1.1	#ifdef BSD
221	greg	1.2	bcopy(op, p, n>on ? on : n);
222	greg	1.1	#else
223	greg	1.2	(void)memcpy(p, op, n>on ? on : n);
224	greg	1.1	#endif
225	greg	1.5	free(op);
226	greg	1.1	return(p);
227			}
228
229
230			free(p) /* free memory allocated by malloc */
231			char *p;
232			{
233			register M_HEAD *mp;
234			register int bucket;
235
236	greg	1.10	if (p == NULL \|\| p == DUMMYLOC)
237	greg	1.2	return;
238	greg	1.1	mp = (M_HEAD *)p - 1;
239			bucket = mp->bucket;
240			mp->next = free_list[bucket];
241			free_list[bucket] = mp;
242	greg	1.9	#ifdef MSTATS
243			m_nfreed += (1 << bucket) + sizeof(M_HEAD);
244			#endif
245	greg	1.1	}
246
247
248			#ifndef NOVMEM
249			#ifndef BSD
250			#include <sys/var.h>
251			int
252			getpagesize() /* use SYSV var structure to get page size */
253			{
254			struct var v;
255
256	greg	1.8	uvar(&v);
257			return(1 << v.v_pageshift);
258	greg	1.1	}
259			#endif
260	greg	1.9	#endif
261
262
263			#ifdef MSTATS
264			printmemstats(fp) /* print memory statistics to stream */
265			FILE *fp;
266			{
267			register int i;
268			int n;
269			register M_HEAD *mp;
270			unsigned int total = 0;
271
272			fprintf(fp, "Memory statistics:\n");
273			fprintf(fp, "\tbmalloc: %d bytes allocated\n", b_nalloced);
274			fprintf(fp, "\tbmalloc: %d bytes freed\n", b_nfreed);
275			fprintf(fp, "\tbmalloc: %d bytes scrounged\n", b_nscrounged);
276			fprintf(fp, "\tmalloc: %d bytes allocated\n", m_nalloced);
277			fprintf(fp, "\tmalloc: %d bytes wasted (%.1f%%)\n", m_nwasted,
278			100.0*m_nwasted/m_nalloced);
279			fprintf(fp, "\tmalloc: %d bytes freed\n", m_nfreed);
280			for (i = NBUCKETS-1; i >= FIRSTBUCKET; i--) {
281			n = 0;
282			for (mp = free_list[i]; mp != NULL; mp = mp->next)
283			n++;
284			if (n) {
285			fprintf(fp, "\t%d * %u\n", n, 1<<i);
286			total += n * ((1<<i) + sizeof(M_HEAD));
287			}
288			}
289			fprintf(fp, "\t %u total bytes in free list\n", total);
290			}
291	greg	1.1	#endif