1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
/* $OpenBSD: rf_memchunk.c,v 1.4 2002/12/16 07:01:04 tdeval Exp $ */
/* $NetBSD: rf_memchunk.c,v 1.4 1999/08/13 03:41:56 oster Exp $ */
/*
* Copyright (c) 1995 Carnegie-Mellon University.
* All rights reserved.
*
* Author: Mark Holland
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*********************************************************************************
* rf_memchunk.c
*
* experimental code. I've found that the malloc and free calls in the DAG
* creation code are very expensive. Since for any given workload the DAGs
* created for different accesses are likely to be similar to each other, the
* amount of memory used for any given DAG data structure is likely to be one
* of a small number of values. For example, in UNIX, all reads and writes will
* be less than 8k and will not span stripe unit boundaries. Thus in the absence
* of failure, the only DAGs that will ever get created are single-node reads
* and single-stripe-unit atomic read-modify-writes. So, I'm very likely to
* be continually asking for chunks of memory equal to the sizes of these two
* DAGs.
*
* This leads to the idea of holding on to these chunks of memory when the DAG is
* freed and then, when a new DAG is created, trying to find such a chunk before
* calling malloc.
*
* the "chunk list" is a list of lists. Each header node contains a size value
* and a pointer to a list of chunk descriptors, each of which holds a pointer
* to a chunk of memory of the indicated size.
*
* There is currently no way to purge memory out of the chunk list. My
* initial thought on this is to have a low-priority thread that wakes up every
* 1 or 2 seconds, purges all the chunks with low reuse counts, and sets all
* the reuse counts to zero.
*
* This whole idea may be bad, since malloc may be able to do this more efficiently.
* It's worth a try, though, and it can be turned off by setting useMemChunks to 0.
*
********************************************************************************/
#include "rf_types.h"
#include "rf_threadstuff.h"
#include "rf_debugMem.h"
#include "rf_memchunk.h"
#include "rf_general.h"
#include "rf_options.h"
#include "rf_shutdown.h"
typedef struct RF_ChunkHdr_s RF_ChunkHdr_t;
struct RF_ChunkHdr_s {
int size;
RF_ChunkDesc_t *list;
RF_ChunkHdr_t *next;
};
static RF_ChunkHdr_t *chunklist, *chunk_hdr_free_list;
static RF_ChunkDesc_t *chunk_desc_free_list;
RF_DECLARE_STATIC_MUTEX(chunkmutex);
void rf_ShutdownMemChunk(void *);
RF_ChunkDesc_t *rf_NewMemChunk(int, char *);
void rf_ShutdownMemChunk(ignored)
void *ignored;
{
RF_ChunkDesc_t *pt, *p;
RF_ChunkHdr_t *hdr, *ht;
if (rf_memChunkDebug)
printf("Chunklist:\n");
for (hdr = chunklist; hdr;) {
for (p = hdr->list; p;) {
if (rf_memChunkDebug)
printf("Size %d reuse count %d\n", p->size, p->reuse_count);
pt = p;
p = p->next;
RF_Free(pt->buf, pt->size);
RF_Free(pt, sizeof(*pt));
}
ht = hdr;
hdr = hdr->next;
RF_Free(ht, sizeof(*ht));
}
rf_mutex_destroy(&chunkmutex);
}
int
rf_ConfigureMemChunk(listp)
RF_ShutdownList_t **listp;
{
int rc;
chunklist = NULL;
chunk_hdr_free_list = NULL;
chunk_desc_free_list = NULL;
rc = rf_mutex_init(&chunkmutex);
if (rc) {
RF_ERRORMSG3("Unable to init mutex file %s line %d rc=%d\n", __FILE__,
__LINE__, rc);
}
rc = rf_ShutdownCreate(listp, rf_ShutdownMemChunk, NULL);
if (rc) {
RF_ERRORMSG3("Unable to add to shutdown list file %s line %d rc=%d\n", __FILE__,
__LINE__, rc);
rf_mutex_destroy(&chunkmutex);
}
return (rc);
}
/* called to get a chunk descriptor for a newly-allocated chunk of memory
* MUTEX MUST BE LOCKED
*
* free list is not currently used
*/
RF_ChunkDesc_t *
rf_NewMemChunk(size, buf)
int size;
char *buf;
{
RF_ChunkDesc_t *p;
if (chunk_desc_free_list) {
p = chunk_desc_free_list;
chunk_desc_free_list = p->next;
} else
RF_Malloc(p, sizeof(RF_ChunkDesc_t), (RF_ChunkDesc_t *));
p->size = size;
p->buf = buf;
p->next = NULL;
p->reuse_count = 0;
return (p);
}
/* looks for a chunk of memory of acceptable size. If none, allocates one and returns
* a chunk descriptor for it, but does not install anything in the list. This is done
* when the chunk is released.
*/
RF_ChunkDesc_t *
rf_GetMemChunk(size)
int size;
{
RF_ChunkHdr_t *hdr = chunklist;
RF_ChunkDesc_t *p = NULL;
char *buf;
RF_LOCK_MUTEX(chunkmutex);
for (hdr = chunklist; hdr; hdr = hdr->next)
if (hdr->size >= size) {
p = hdr->list;
if (p) {
hdr->list = p->next;
p->next = NULL;
p->reuse_count++;
}
break;
}
if (!p) {
RF_Malloc(buf, size, (char *));
p = rf_NewMemChunk(size, buf);
}
RF_UNLOCK_MUTEX(chunkmutex);
(void) bzero(p->buf, size);
return (p);
}
void
rf_ReleaseMemChunk(chunk)
RF_ChunkDesc_t *chunk;
{
RF_ChunkHdr_t *hdr, *ht = NULL, *new;
RF_LOCK_MUTEX(chunkmutex);
for (hdr = chunklist; hdr && hdr->size < chunk->size; ht = hdr, hdr = hdr->next);
if (hdr && hdr->size == chunk->size) {
chunk->next = hdr->list;
hdr->list = chunk;
} else {
RF_Malloc(new, sizeof(RF_ChunkHdr_t), (RF_ChunkHdr_t *));
new->size = chunk->size;
new->list = chunk;
chunk->next = NULL;
if (ht) {
new->next = ht->next;
ht->next = new;
} else {
new->next = hdr;
chunklist = new;
}
}
RF_UNLOCK_MUTEX(chunkmutex);
}
|
