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
|
/*
* 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 "qemu/osdep.h"
#include "qapi/qmp/qerror.h"
#include "qapi/error.h"
#include "qemu/host-utils.h"
#include "page_cache.h"
#include "trace.h"
/* the page in cache will not be replaced in two cycles */
#define CACHED_PAGE_LIFETIME 2
typedef struct CacheItem CacheItem;
struct CacheItem {
uint64_t it_addr;
uint64_t it_age;
uint8_t *it_data;
};
struct PageCache {
CacheItem *page_cache;
size_t page_size;
size_t max_num_items;
size_t num_items;
};
PageCache *cache_init(int64_t new_size, size_t page_size, Error **errp)
{
int64_t i;
size_t num_pages = new_size / page_size;
PageCache *cache;
if (new_size < page_size) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"is smaller than one target page size");
return NULL;
}
/* round down to the nearest power of 2 */
if (!is_power_of_2(num_pages)) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"is not a power of two number of pages");
return NULL;
}
/* We prefer not to abort if there is no memory */
cache = g_try_malloc(sizeof(*cache));
if (!cache) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"Failed to allocate cache");
return NULL;
}
cache->page_size = page_size;
cache->num_items = 0;
cache->max_num_items = num_pages;
trace_migration_pagecache_init(cache->max_num_items);
/* We prefer not to abort if there is no memory */
cache->page_cache = g_try_malloc((cache->max_num_items) *
sizeof(*cache->page_cache));
if (!cache->page_cache) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"Failed to allocate page cache");
g_free(cache);
return NULL;
}
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;
g_free(cache);
}
static size_t cache_get_cache_pos(const PageCache *cache,
uint64_t address)
{
g_assert(cache->max_num_items);
return (address / cache->page_size) & (cache->max_num_items - 1);
}
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;
}
bool cache_is_cached(const PageCache *cache, uint64_t addr,
uint64_t current_age)
{
CacheItem *it;
it = cache_get_by_addr(cache, addr);
if (it->it_addr == addr) {
/* update the it_age when the cache hit */
it->it_age = current_age;
return true;
}
return false;
}
int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata,
uint64_t current_age)
{
CacheItem *it;
/* actual update of entry */
it = cache_get_by_addr(cache, addr);
if (it->it_data && it->it_addr != addr &&
it->it_age + CACHED_PAGE_LIFETIME > current_age) {
/* the cache page is fresh, don't replace it */
return -1;
}
/* allocate page */
if (!it->it_data) {
it->it_data = g_try_malloc(cache->page_size);
if (!it->it_data) {
trace_migration_pagecache_insert();
return -1;
}
cache->num_items++;
}
memcpy(it->it_data, pdata, cache->page_size);
it->it_age = current_age;
it->it_addr = addr;
return 0;
}
|
