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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 | #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_cleanup_fn *elevator_merge_cleanup_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 ELEVATOR_NOOP \ ((elevator_t) { \ 0, /* read_latency */ \ 0, /* write_latency */ \ \ elevator_noop_merge, /* elevator_merge_fn */ \ elevator_noop_merge_cleanup, /* elevator_merge_cleanup_fn */ \ elevator_noop_merge_req, /* elevator_merge_req_fn */ \ }) #define ELEVATOR_LINUS \ ((elevator_t) { \ 8192, /* read passovers */ \ 16384, /* write passovers */ \ \ elevator_linus_merge, /* elevator_merge_fn */ \ elevator_linus_merge_cleanup, /* elevator_merge_cleanup_fn */ \ elevator_linus_merge_req, /* elevator_merge_req_fn */ \ }) #endif |