1/* $NetBSD: bufq_readprio.c,v 1.16 2017/05/04 11:03:27 kamil 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_readprio.c,v 1.16 2017/05/04 11:03:27 kamil 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#include <sys/module.h> 80 81/* 82 * Seek sort for disks. 83 * 84 * There are two queues. The first queue holds read requests; the second 85 * holds write requests. The read queue is first-come first-served; the 86 * write queue is sorted in ascendening block order. 87 * The read queue is processed first. After PRIO_READ_BURST consecutive 88 * read requests with non-empty write queue PRIO_WRITE_REQ requests from 89 * the write queue will be processed. 90 */ 91 92#define PRIO_READ_BURST 48 93#define PRIO_WRITE_REQ 16 94 95struct bufq_prio { 96 TAILQ_HEAD(, buf) bq_read, bq_write; /* actual list of buffers */ 97 struct buf *bq_write_next; /* next request in bq_write */ 98 struct buf *bq_next; /* current request */ 99 int bq_read_burst; /* # of consecutive reads */ 100}; 101 102static void bufq_readprio_init(struct bufq_state *); 103static void bufq_prio_put(struct bufq_state *, struct buf *); 104static struct buf *bufq_prio_get(struct bufq_state *, int); 105 106BUFQ_DEFINE(readprio, 30, bufq_readprio_init); 107 108static void 109bufq_prio_put(struct bufq_state *bufq, struct buf *bp) 110{ 111 struct bufq_prio *prio = bufq_private(bufq); 112 struct buf *bq; 113 int sortby; 114 115 sortby = bufq->bq_flags & BUFQ_SORT_MASK; 116 117 /* 118 * If it's a read request append it to the list. 119 */ 120 if ((bp->b_flags & B_READ) == B_READ) { 121 TAILQ_INSERT_TAIL(&prio->bq_read, bp, b_actq); 122 return; 123 } 124 125 bq = TAILQ_FIRST(&prio->bq_write); 126 127 /* 128 * If the write list is empty, simply append it to the list. 129 */ 130 if (bq == NULL) { 131 TAILQ_INSERT_TAIL(&prio->bq_write, bp, b_actq); 132 prio->bq_write_next = bp; 133 return; 134 } 135 136 /* 137 * If we lie after the next request, insert after this request. 138 */ 139 if (buf_inorder(prio->bq_write_next, bp, sortby)) 140 bq = prio->bq_write_next; 141 142 /* 143 * Search for the first request at a larger block number. 144 * We go before this request if it exists. 145 */ 146 while (bq != NULL && buf_inorder(bq, bp, sortby)) 147 bq = TAILQ_NEXT(bq, b_actq); 148 149 if (bq != NULL) 150 TAILQ_INSERT_BEFORE(bq, bp, b_actq); 151 else 152 TAILQ_INSERT_TAIL(&prio->bq_write, bp, b_actq); 153} 154 155static struct buf * 156bufq_prio_get(struct bufq_state *bufq, int remove) 157{ 158 struct bufq_prio *prio = bufq_private(bufq); 159 struct buf *bp; 160 161 /* 162 * If no current request, get next from the lists. 163 */ 164 if (prio->bq_next == NULL) { 165 /* 166 * If at least one list is empty, select the other. 167 */ 168 if (TAILQ_FIRST(&prio->bq_read) == NULL) { 169 prio->bq_next = prio->bq_write_next; 170 prio->bq_read_burst = 0; 171 } else if (prio->bq_write_next == NULL) { 172 bp = prio->bq_next = TAILQ_FIRST(&prio->bq_read); 173 prio->bq_read_burst = 0; 174 KASSERT((bp == NULL) || 175 ((bp->b_flags & B_READ) == B_READ)); 176 } else { 177 /* 178 * Both list have requests. Select the read list up 179 * to PRIO_READ_BURST times, then select the write 180 * list PRIO_WRITE_REQ times. 181 */ 182 if (prio->bq_read_burst++ < PRIO_READ_BURST) 183 prio->bq_next = TAILQ_FIRST(&prio->bq_read); 184 else if (prio->bq_read_burst < 185 PRIO_READ_BURST + PRIO_WRITE_REQ) 186 prio->bq_next = prio->bq_write_next; 187 else { 188 prio->bq_next = TAILQ_FIRST(&prio->bq_read); 189 prio->bq_read_burst = 0; 190 } 191 } 192 } 193 194 bp = prio->bq_next; 195 196 if (bp != NULL && remove) { 197 if ((bp->b_flags & B_READ) == B_READ) 198 TAILQ_REMOVE(&prio->bq_read, bp, b_actq); 199 else { 200 /* 201 * Advance the write pointer before removing 202 * bp since it is actually prio->bq_write_next. 203 */ 204 prio->bq_write_next = 205 TAILQ_NEXT(prio->bq_write_next, b_actq); 206 TAILQ_REMOVE(&prio->bq_write, bp, b_actq); 207 if (prio->bq_write_next == NULL) 208 prio->bq_write_next = 209 TAILQ_FIRST(&prio->bq_write); 210 } 211 212 prio->bq_next = NULL; 213 } 214 215 return (bp); 216} 217 218static struct buf * 219bufq_prio_cancel(struct bufq_state *bufq, struct buf *buf) 220{ 221 struct bufq_prio *prio = bufq_private(bufq); 222 struct buf *bq; 223 224 /* search read queue */ 225 TAILQ_FOREACH(bq, &prio->bq_read, b_actq) { 226 if (bq == buf) { 227 TAILQ_REMOVE(&prio->bq_read, bq, b_actq); 228 /* force new section */ 229 prio->bq_next = NULL; 230 return buf; 231 } 232 } 233 234 /* not found in read queue, search write queue */ 235 TAILQ_FOREACH(bq, &prio->bq_write, b_actq) { 236 if (bq == buf) { 237 if (bq == prio->bq_write_next) { 238 /* 239 * Advance the write pointer before removing 240 * bp since it is actually prio->bq_write_next. 241 */ 242 prio->bq_write_next = 243 TAILQ_NEXT(prio->bq_write_next, b_actq); 244 TAILQ_REMOVE(&prio->bq_write, bq, b_actq); 245 if (prio->bq_write_next == NULL) 246 prio->bq_write_next = 247 TAILQ_FIRST(&prio->bq_write); 248 } else { 249 TAILQ_REMOVE(&prio->bq_write, bq, b_actq); 250 } 251 /* force new section */ 252 prio->bq_next = NULL; 253 return buf; 254 } 255 } 256 257 /* still not found */ 258 return NULL; 259} 260 261static void 262bufq_prio_fini(struct bufq_state *bufq) 263{ 264 265 KASSERT(bufq->bq_private != NULL); 266 kmem_free(bufq->bq_private, sizeof(struct bufq_prio)); 267} 268 269static void 270bufq_readprio_init(struct bufq_state *bufq) 271{ 272 struct bufq_prio *prio; 273 274 bufq->bq_get = bufq_prio_get; 275 bufq->bq_put = bufq_prio_put; 276 bufq->bq_cancel = bufq_prio_cancel; 277 bufq->bq_fini = bufq_prio_fini; 278 bufq->bq_private = kmem_zalloc(sizeof(struct bufq_prio), KM_SLEEP); 279 prio = (struct bufq_prio *)bufq->bq_private; 280 TAILQ_INIT(&prio->bq_read); 281 TAILQ_INIT(&prio->bq_write); 282} 283 284MODULE(MODULE_CLASS_BUFQ, bufq_readprio, NULL); 285 286static int 287bufq_readprio_modcmd(modcmd_t cmd, void *opaque) 288{ 289 290 switch (cmd) { 291 case MODULE_CMD_INIT: 292 return bufq_register(&bufq_strat_readprio); 293 case MODULE_CMD_FINI: 294 return bufq_unregister(&bufq_strat_readprio); 295 default: 296 return ENOTTY; 297 } 298} 299