1 /* $NetBSD: bufq_disksort.c,v 1.11 2009/01/19 14:54:28 yamt 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 * 21 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 23 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 24 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 31 * POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 /* 35 * Copyright (c) 1982, 1986, 1988, 1993 36 * The Regents of the University of California. All rights reserved. 37 * (c) UNIX System Laboratories, Inc. 38 * All or some portions of this file are derived from material licensed 39 * to the University of California by American Telephone and Telegraph 40 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 41 * the permission of UNIX System Laboratories, Inc. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. Neither the name of the University nor the names of its contributors 52 * may be used to endorse or promote products derived from this software 53 * without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 65 * SUCH DAMAGE. 66 * 67 * @(#)ufs_disksubr.c 8.5 (Berkeley) 1/21/94 68 */ 69 70 #include <sys/cdefs.h> 71 __KERNEL_RCSID(0, "$NetBSD: bufq_disksort.c,v 1.11 2009/01/19 14:54:28 yamt Exp $"); 72 73 #include <sys/param.h> 74 #include <sys/systm.h> 75 #include <sys/buf.h> 76 #include <sys/bufq.h> 77 #include <sys/bufq_impl.h> 78 #include <sys/kmem.h> 79 80 /* 81 * Seek sort for disks. 82 * 83 * There are actually two queues, sorted in ascendening order. The first 84 * queue holds those requests which are positioned after the current block; 85 * the second holds requests which came in after their position was passed. 86 * Thus we implement a one-way scan, retracting after reaching the end of 87 * the drive to the first request on the second queue, at which time it 88 * becomes the first queue. 89 * 90 * A one-way scan is natural because of the way UNIX read-ahead blocks are 91 * allocated. 92 */ 93 94 struct bufq_disksort { 95 TAILQ_HEAD(, buf) bq_head; /* actual list of buffers */ 96 }; 97 98 static void bufq_disksort_init(struct bufq_state *); 99 static void bufq_disksort_put(struct bufq_state *, struct buf *); 100 static struct buf *bufq_disksort_get(struct bufq_state *, int); 101 102 BUFQ_DEFINE(disksort, 20, bufq_disksort_init); 103 104 static void 105 bufq_disksort_put(struct bufq_state *bufq, struct buf *bp) 106 { 107 struct bufq_disksort *disksort = bufq_private(bufq); 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 static struct buf * 195 bufq_disksort_cancel(struct bufq_state *bufq, struct buf *buf) 196 { 197 struct bufq_disksort *disksort = bufq->bq_private; 198 struct buf *bq; 199 200 TAILQ_FOREACH(bq, &disksort->bq_head, b_actq) { 201 if (bq == buf) { 202 TAILQ_REMOVE(&disksort->bq_head, bq, b_actq); 203 return buf; 204 } 205 } 206 return NULL; 207 } 208 209 static void 210 bufq_disksort_fini(struct bufq_state *bufq) 211 { 212 213 KASSERT(bufq->bq_private != NULL); 214 kmem_free(bufq->bq_private, sizeof(struct bufq_disksort)); 215 } 216 217 static void 218 bufq_disksort_init(struct bufq_state *bufq) 219 { 220 struct bufq_disksort *disksort; 221 222 disksort = kmem_zalloc(sizeof(*disksort), KM_SLEEP); 223 bufq->bq_private = disksort; 224 bufq->bq_get = bufq_disksort_get; 225 bufq->bq_put = bufq_disksort_put; 226 bufq->bq_cancel = bufq_disksort_cancel; 227 bufq->bq_fini = bufq_disksort_fini; 228 TAILQ_INIT(&disksort->bq_head); 229 } 230