1 /* $NetBSD: bufq_disksort.c,v 1.6 2005/12/11 12:24:29 christos Exp $ */
2 /* NetBSD: subr_disk.c,v 1.61 2004/09/25 03:30:44 thorpej Exp */
3
4 /*-
5 * Copyright (c) 1996, 1997, 1999, 2000 The NetBSD Foundation, Inc.
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to The NetBSD Foundation
9 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
10 * NASA Ames Research Center.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the NetBSD
23 * Foundation, Inc. and its contributors.
24 * 4. Neither the name of The NetBSD Foundation nor the names of its
25 * contributors may be used to endorse or promote products derived
26 * from this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
29 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
30 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
31 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
32 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
33 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
34 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
35 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
36 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
37 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38 * POSSIBILITY OF SUCH DAMAGE.
39 */
40
41 /*
42 * Copyright (c) 1982, 1986, 1988, 1993
43 * The Regents of the University of California. All rights reserved.
44 * (c) UNIX System Laboratories, Inc.
45 * All or some portions of this file are derived from material licensed
46 * to the University of California by American Telephone and Telegraph
47 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
48 * the permission of UNIX System Laboratories, Inc.
49 *
50 * Redistribution and use in source and binary forms, with or without
51 * modification, are permitted provided that the following conditions
52 * are met:
53 * 1. Redistributions of source code must retain the above copyright
54 * notice, this list of conditions and the following disclaimer.
55 * 2. Redistributions in binary form must reproduce the above copyright
56 * notice, this list of conditions and the following disclaimer in the
57 * documentation and/or other materials provided with the distribution.
58 * 3. Neither the name of the University nor the names of its contributors
59 * may be used to endorse or promote products derived from this software
60 * without specific prior written permission.
61 *
62 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
63 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
64 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
65 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
66 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
67 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
68 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
69 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
70 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
71 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
72 * SUCH DAMAGE.
73 *
74 * @(#)ufs_disksubr.c 8.5 (Berkeley) 1/21/94
75 */
76
77 #include <sys/cdefs.h>
78 __KERNEL_RCSID(0, "$NetBSD: bufq_disksort.c,v 1.6 2005/12/11 12:24:29 christos Exp $");
79
80 #include <sys/param.h>
81 #include <sys/systm.h>
82 #include <sys/buf.h>
83 #include <sys/bufq.h>
84 #include <sys/bufq_impl.h>
85 #include <sys/malloc.h>
86
87 /*
88 * Seek sort for disks.
89 *
90 * There are actually two queues, sorted in ascendening order. The first
91 * queue holds those requests which are positioned after the current block;
92 * the second holds requests which came in after their position was passed.
93 * Thus we implement a one-way scan, retracting after reaching the end of
94 * the drive to the first request on the second queue, at which time it
95 * becomes the first queue.
96 *
97 * A one-way scan is natural because of the way UNIX read-ahead blocks are
98 * allocated.
99 */
100
101 struct bufq_disksort {
102 TAILQ_HEAD(, buf) bq_head; /* actual list of buffers */
103 };
104
105 static void bufq_disksort_init(struct bufq_state *);
106 static void bufq_disksort_put(struct bufq_state *, struct buf *);
107 static struct buf *bufq_disksort_get(struct bufq_state *, int);
108
109 BUFQ_DEFINE(disksort, 20, bufq_disksort_init);
110
111 static void
112 bufq_disksort_put(struct bufq_state *bufq, struct buf *bp)
113 {
114 struct bufq_disksort *disksort = bufq_private(bufq);
115 struct buf *bq, *nbq;
116 int sortby;
117
118 sortby = bufq->bq_flags & BUFQ_SORT_MASK;
119
120 bq = TAILQ_FIRST(&disksort->bq_head);
121
122 /*
123 * If the queue is empty it's easy; we just go on the end.
124 */
125 if (bq == NULL) {
126 TAILQ_INSERT_TAIL(&disksort->bq_head, bp, b_actq);
127 return;
128 }
129
130 /*
131 * If we lie before the currently active request, then we
132 * must locate the second request list and add ourselves to it.
133 */
134 if (buf_inorder(bp, bq, sortby)) {
135 while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) {
136 /*
137 * Check for an ``inversion'' in the normally ascending
138 * block numbers, indicating the start of the second
139 * request list.
140 */
141 if (buf_inorder(nbq, bq, sortby)) {
142 /*
143 * Search the second request list for the first
144 * request at a larger block number. We go
145 * after that; if there is no such request, we
146 * go at the end.
147 */
148 do {
149 if (buf_inorder(bp, nbq, sortby))
150 goto insert;
151 bq = nbq;
152 } while ((nbq =
153 TAILQ_NEXT(bq, b_actq)) != NULL);
154 goto insert; /* after last */
155 }
156 bq = nbq;
157 }
158 /*
159 * No inversions... we will go after the last, and
160 * be the first request in the second request list.
161 */
162 goto insert;
163 }
164 /*
165 * Request is at/after the current request...
166 * sort in the first request list.
167 */
168 while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) {
169 /*
170 * We want to go after the current request if there is an
171 * inversion after it (i.e. it is the end of the first
172 * request list), or if the next request is a larger cylinder
173 * than our request.
174 */
175 if (buf_inorder(nbq, bq, sortby) ||
176 buf_inorder(bp, nbq, sortby))
177 goto insert;
178 bq = nbq;
179 }
180 /*
181 * Neither a second list nor a larger request... we go at the end of
182 * the first list, which is the same as the end of the whole schebang.
183 */
184 insert: TAILQ_INSERT_AFTER(&disksort->bq_head, bq, bp, b_actq);
185 }
186
187 static struct buf *
188 bufq_disksort_get(struct bufq_state *bufq, int remove)
189 {
190 struct bufq_disksort *disksort = bufq->bq_private;
191 struct buf *bp;
192
193 bp = TAILQ_FIRST(&disksort->bq_head);
194
195 if (bp != NULL && remove)
196 TAILQ_REMOVE(&disksort->bq_head, bp, b_actq);
197
198 return (bp);
199 }
200
201 static void
202 bufq_disksort_init(struct bufq_state *bufq)
203 {
204 struct bufq_disksort *disksort;
205
206 bufq->bq_get = bufq_disksort_get;
207 bufq->bq_put = bufq_disksort_put;
208 bufq->bq_private = malloc(sizeof(struct bufq_disksort),
209 M_DEVBUF, M_ZERO);
210 disksort = (struct bufq_disksort *)bufq->bq_private;
211 TAILQ_INIT(&disksort->bq_head);
212 }
Cache object: cb864d36db4ac25a0224cfb543b1acb0
|