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
212
213
214
215
216
217
218
219
220
221
|
/*
* Page cache for QEMU
* The cache is base on a hash of the page address
*
* Copyright 2012 Red Hat, Inc. and/or its affiliates
*
* Authors:
* Orit Wasserman <owasserm@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <string.h>
#include <sys/time.h>
#include <sys/types.h>
#include <stdbool.h>
#include <glib.h>
#include <strings.h>
#include "qemu-common.h"
#include "migration/page_cache.h"
#ifdef DEBUG_CACHE
#define DPRINTF(fmt, ...) \
do { fprintf(stdout, "cache: " fmt, ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) \
do { } while (0)
#endif
typedef struct CacheItem CacheItem;
struct CacheItem {
uint64_t it_addr;
uint64_t it_age;
uint8_t *it_data;
};
struct PageCache {
CacheItem *page_cache;
unsigned int page_size;
int64_t max_num_items;
uint64_t max_item_age;
int64_t num_items;
};
PageCache *cache_init(int64_t num_pages, unsigned int page_size)
{
int64_t i;
PageCache *cache;
if (num_pages <= 0) {
DPRINTF("invalid number of pages\n");
return NULL;
}
cache = g_malloc(sizeof(*cache));
/* round down to the nearest power of 2 */
if (!is_power_of_2(num_pages)) {
num_pages = pow2floor(num_pages);
DPRINTF("rounding down to %" PRId64 "\n", num_pages);
}
cache->page_size = page_size;
cache->num_items = 0;
cache->max_item_age = 0;
cache->max_num_items = num_pages;
DPRINTF("Setting cache buckets to %" PRId64 "\n", cache->max_num_items);
cache->page_cache = g_malloc((cache->max_num_items) *
sizeof(*cache->page_cache));
for (i = 0; i < cache->max_num_items; i++) {
cache->page_cache[i].it_data = NULL;
cache->page_cache[i].it_age = 0;
cache->page_cache[i].it_addr = -1;
}
return cache;
}
void cache_fini(PageCache *cache)
{
int64_t i;
g_assert(cache);
g_assert(cache->page_cache);
for (i = 0; i < cache->max_num_items; i++) {
g_free(cache->page_cache[i].it_data);
}
g_free(cache->page_cache);
cache->page_cache = NULL;
}
static size_t cache_get_cache_pos(const PageCache *cache,
uint64_t address)
{
size_t pos;
g_assert(cache->max_num_items);
pos = (address / cache->page_size) & (cache->max_num_items - 1);
return pos;
}
bool cache_is_cached(const PageCache *cache, uint64_t addr)
{
size_t pos;
g_assert(cache);
g_assert(cache->page_cache);
pos = cache_get_cache_pos(cache, addr);
return (cache->page_cache[pos].it_addr == addr);
}
static CacheItem *cache_get_by_addr(const PageCache *cache, uint64_t addr)
{
size_t pos;
g_assert(cache);
g_assert(cache->page_cache);
pos = cache_get_cache_pos(cache, addr);
return &cache->page_cache[pos];
}
uint8_t *get_cached_data(const PageCache *cache, uint64_t addr)
{
return cache_get_by_addr(cache, addr)->it_data;
}
void cache_insert(PageCache *cache, uint64_t addr, uint8_t *pdata)
{
CacheItem *it = NULL;
g_assert(cache);
g_assert(cache->page_cache);
/* actual update of entry */
it = cache_get_by_addr(cache, addr);
/* free old cached data if any */
g_free(it->it_data);
if (!it->it_data) {
cache->num_items++;
}
it->it_data = g_memdup(pdata, cache->page_size);
it->it_age = ++cache->max_item_age;
it->it_addr = addr;
}
int64_t cache_resize(PageCache *cache, int64_t new_num_pages)
{
PageCache *new_cache;
int64_t i;
CacheItem *old_it, *new_it;
g_assert(cache);
/* cache was not inited */
if (cache->page_cache == NULL) {
return -1;
}
/* same size */
if (pow2floor(new_num_pages) == cache->max_num_items) {
return cache->max_num_items;
}
new_cache = cache_init(new_num_pages, cache->page_size);
if (!(new_cache)) {
DPRINTF("Error creating new cache\n");
return -1;
}
/* move all data from old cache */
for (i = 0; i < cache->max_num_items; i++) {
old_it = &cache->page_cache[i];
if (old_it->it_addr != -1) {
/* check for collision, if there is, keep MRU page */
new_it = cache_get_by_addr(new_cache, old_it->it_addr);
if (new_it->it_data && new_it->it_age >= old_it->it_age) {
/* keep the MRU page */
g_free(old_it->it_data);
} else {
if (!new_it->it_data) {
new_cache->num_items++;
}
g_free(new_it->it_data);
new_it->it_data = old_it->it_data;
new_it->it_age = old_it->it_age;
new_it->it_addr = old_it->it_addr;
}
}
}
g_free(cache->page_cache);
cache->page_cache = new_cache->page_cache;
cache->max_num_items = new_cache->max_num_items;
cache->num_items = new_cache->num_items;
g_free(new_cache);
return cache->max_num_items;
}
|
