blob: ad8aa35bae00e9836bcb96f0efbd3f8b781b2705 (
plain)
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
|
/*
* Compressed RAM block device
*
* Copyright (C) 2008, 2009, 2010 Nitin Gupta
* 2012, 2013 Minchan Kim
*
* This code is released using a dual license strategy: BSD/GPL
* You can choose the licence that better fits your requirements.
*
* Released under the terms of 3-clause BSD License
* Released under the terms of GNU General Public License Version 2.0
*
*/
#ifndef _ZRAM_DRV_H_
#define _ZRAM_DRV_H_
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/zsmalloc.h>
/*
* Some arbitrary value. This is just to catch
* invalid value for num_devices module parameter.
*/
static const unsigned max_num_devices = 32;
/*-- Configurable parameters */
/*
* Pages that compress to size greater than this are stored
* uncompressed in memory.
*/
static const size_t max_zpage_size = PAGE_SIZE / 4 * 3;
/*
* NOTE: max_zpage_size must be less than or equal to:
* ZS_MAX_ALLOC_SIZE. Otherwise, zs_malloc() would
* always return failure.
*/
/*-- End of configurable params */
#define SECTOR_SHIFT 9
#define SECTOR_SIZE (1 << SECTOR_SHIFT)
#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT)
#define ZRAM_LOGICAL_BLOCK_SHIFT 12
#define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT)
#define ZRAM_SECTOR_PER_LOGICAL_BLOCK \
(1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT))
/* Flags for zram pages (table[page_no].flags) */
enum zram_pageflags {
/* Page consists entirely of zeros */
ZRAM_ZERO,
__NR_ZRAM_PAGEFLAGS,
};
/*-- Data structures */
/* Allocated for each disk page */
struct table {
unsigned long handle;
u16 size; /* object size (excluding header) */
u8 count; /* object ref count (not yet used) */
u8 flags;
} __aligned(4);
struct zram_stats {
atomic64_t compr_size; /* compressed size of pages stored */
atomic64_t num_reads; /* failed + successful */
atomic64_t num_writes; /* --do-- */
atomic64_t failed_reads; /* should NEVER! happen */
atomic64_t failed_writes; /* can happen when memory is too low */
atomic64_t invalid_io; /* non-page-aligned I/O requests */
atomic64_t notify_free; /* no. of swap slot free notifications */
atomic_t pages_zero; /* no. of zero filled pages */
atomic_t pages_stored; /* no. of pages currently stored */
atomic_t good_compress; /* % of pages with compression ratio<=50% */
atomic_t bad_compress; /* % of pages with compression ratio>=75% */
};
struct zram_meta {
rwlock_t tb_lock; /* protect table */
void *compress_workmem;
void *compress_buffer;
struct table *table;
struct zs_pool *mem_pool;
struct mutex buffer_lock; /* protect compress buffers */
};
struct zram {
struct zram_meta *meta;
struct request_queue *queue;
struct gendisk *disk;
int init_done;
/* Prevent concurrent execution of device init, reset and R/W request */
struct rw_semaphore init_lock;
/*
* This is the limit on amount of *uncompressed* worth of data
* we can store in a disk.
*/
u64 disksize; /* bytes */
struct zram_stats stats;
};
#endif
|
