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
|
#ifndef _LINUX_ELEVATOR_H
#define _LINUX_ELEVATOR_H
typedef void (elevator_fn) (struct request *, elevator_t *,
struct list_head *,
struct list_head *, int);
typedef int (elevator_merge_fn) (request_queue_t *, struct request **, struct list_head *,
struct buffer_head *, int, int);
typedef void (elevator_merge_cleanup_fn) (request_queue_t *, struct request *, int);
typedef void (elevator_merge_req_fn) (struct request *, struct request *);
struct elevator_s
{
int read_latency;
int write_latency;
elevator_merge_fn *elevator_merge_fn;
elevator_merge_req_fn *elevator_merge_req_fn;
unsigned int queue_ID;
};
int elevator_noop_merge(request_queue_t *, struct request **, struct list_head *, struct buffer_head *, int, int);
void elevator_noop_merge_cleanup(request_queue_t *, struct request *, int);
void elevator_noop_merge_req(struct request *, struct request *);
int elevator_linus_merge(request_queue_t *, struct request **, struct list_head *, struct buffer_head *, int, int);
void elevator_linus_merge_cleanup(request_queue_t *, struct request *, int);
void elevator_linus_merge_req(struct request *, struct request *);
typedef struct blkelv_ioctl_arg_s {
int queue_ID;
int read_latency;
int write_latency;
int max_bomb_segments;
} blkelv_ioctl_arg_t;
#define BLKELVGET _IOR(0x12,106,sizeof(blkelv_ioctl_arg_t))
#define BLKELVSET _IOW(0x12,107,sizeof(blkelv_ioctl_arg_t))
extern int blkelvget_ioctl(elevator_t *, blkelv_ioctl_arg_t *);
extern int blkelvset_ioctl(elevator_t *, const blkelv_ioctl_arg_t *);
extern void elevator_init(elevator_t *, elevator_t);
/*
* Return values from elevator merger
*/
#define ELEVATOR_NO_MERGE 0
#define ELEVATOR_FRONT_MERGE 1
#define ELEVATOR_BACK_MERGE 2
/*
* This is used in the elevator algorithm. We don't prioritise reads
* over writes any more --- although reads are more time-critical than
* writes, by treating them equally we increase filesystem throughput.
* This turns out to give better overall performance. -- sct
*/
#define IN_ORDER(s1,s2) \
((((s1)->rq_dev == (s2)->rq_dev && \
(s1)->sector < (s2)->sector)) || \
(s1)->rq_dev < (s2)->rq_dev)
#define BHRQ_IN_ORDER(bh, rq) \
((((bh)->b_rdev == (rq)->rq_dev && \
(bh)->b_rsector < (rq)->sector)) || \
(bh)->b_rdev < (rq)->rq_dev)
static inline int elevator_request_latency(elevator_t * elevator, int rw)
{
int latency;
latency = elevator->read_latency;
if (rw != READ)
latency = elevator->write_latency;
return latency;
}
#define ELV_LINUS_SEEK_COST 16
#define ELEVATOR_NOOP \
((elevator_t) { \
0, /* read_latency */ \
0, /* write_latency */ \
\
elevator_noop_merge, /* elevator_merge_fn */ \
elevator_noop_merge_req, /* elevator_merge_req_fn */ \
})
#define ELEVATOR_LINUS \
((elevator_t) { \
2048, /* read passovers */ \
8192, /* write passovers */ \
\
elevator_linus_merge, /* elevator_merge_fn */ \
elevator_linus_merge_req, /* elevator_merge_req_fn */ \
})
#endif
|
