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 } 213