bufq_disksort.c revision 1.1.2.3
1 /* $NetBSD: bufq_disksort.c,v 1.1.2.3 2004/11/02 07:53:23 skrll 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 1.1.2.3 2004/11/02 07:53:23 skrll 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/malloc.h> 85 86 /* 87 * Seek sort for disks. 88 * 89 * There are actually two queues, sorted in ascendening order. The first 90 * queue holds those requests which are positioned after the current block; 91 * the second holds requests which came in after their position was passed. 92 * Thus we implement a one-way scan, retracting after reaching the end of 93 * the drive to the first request on the second queue, at which time it 94 * becomes the first queue. 95 * 96 * A one-way scan is natural because of the way UNIX read-ahead blocks are 97 * allocated. 98 */ 99 100 struct bufq_disksort { 101 TAILQ_HEAD(, buf) bq_head; /* actual list of buffers */ 102 }; 103 104 static void 105 bufq_disksort_put(struct bufq_state *bufq, struct buf *bp) 106 { 107 struct bufq_disksort *disksort = bufq->bq_private; 108 struct buf *bq, *nbq; 109 int sortby; 110 111 sortby = bufq->bq_flags & BUFQ_SORT_MASK; 112 113 bq = TAILQ_FIRST(&disksort->bq_head); 114 115 /* 116 * If the queue is empty it's easy; we just go on the end. 117 */ 118 if (bq == NULL) { 119 TAILQ_INSERT_TAIL(&disksort->bq_head, bp, b_actq); 120 return; 121 } 122 123 /* 124 * If we lie before the currently active request, then we 125 * must locate the second request list and add ourselves to it. 126 */ 127 if (buf_inorder(bp, bq, sortby)) { 128 while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) { 129 /* 130 * Check for an ``inversion'' in the normally ascending 131 * block numbers, indicating the start of the second 132 * request list. 133 */ 134 if (buf_inorder(nbq, bq, sortby)) { 135 /* 136 * Search the second request list for the first 137 * request at a larger block number. We go 138 * after that; if there is no such request, we 139 * go at the end. 140 */ 141 do { 142 if (buf_inorder(bp, nbq, sortby)) 143 goto insert; 144 bq = nbq; 145 } while ((nbq = 146 TAILQ_NEXT(bq, b_actq)) != NULL); 147 goto insert; /* after last */ 148 } 149 bq = nbq; 150 } 151 /* 152 * No inversions... we will go after the last, and 153 * be the first request in the second request list. 154 */ 155 goto insert; 156 } 157 /* 158 * Request is at/after the current request... 159 * sort in the first request list. 160 */ 161 while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) { 162 /* 163 * We want to go after the current request if there is an 164 * inversion after it (i.e. it is the end of the first 165 * request list), or if the next request is a larger cylinder 166 * than our request. 167 */ 168 if (buf_inorder(nbq, bq, sortby) || 169 buf_inorder(bp, nbq, sortby)) 170 goto insert; 171 bq = nbq; 172 } 173 /* 174 * Neither a second list nor a larger request... we go at the end of 175 * the first list, which is the same as the end of the whole schebang. 176 */ 177 insert: TAILQ_INSERT_AFTER(&disksort->bq_head, bq, bp, b_actq); 178 } 179 180 static struct buf * 181 bufq_disksort_get(struct bufq_state *bufq, int remove) 182 { 183 struct bufq_disksort *disksort = bufq->bq_private; 184 struct buf *bp; 185 186 bp = TAILQ_FIRST(&disksort->bq_head); 187 188 if (bp != NULL && remove) 189 TAILQ_REMOVE(&disksort->bq_head, bp, b_actq); 190 191 return (bp); 192 } 193 194 void 195 bufq_disksort_init(struct bufq_state *bufq) 196 { 197 struct bufq_disksort *disksort; 198 199 bufq->bq_get = bufq_disksort_get; 200 bufq->bq_put = bufq_disksort_put; 201 MALLOC(bufq->bq_private, struct bufq_disksort *, 202 sizeof(struct bufq_disksort), M_DEVBUF, M_ZERO); 203 disksort = (struct bufq_disksort *)bufq->bq_private; 204 TAILQ_INIT(&disksort->bq_head); 205 } 206
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