5fc434dc18
BUFQ_CANCEL(queue, element) removes the specified element previously queued on the queue. It returns NULL if it was not found on the queue and the element if it was successfully removed. Run trough tech-kern and changed name from BUFQ_REVOKE() by suggestion of Jason Thorpe.
278 lines
8.8 KiB
C
278 lines
8.8 KiB
C
/* $NetBSD: bufq_readprio.c,v 1.11 2008/04/30 12:09:02 reinoud Exp $ */
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/* NetBSD: subr_disk.c,v 1.61 2004/09/25 03:30:44 thorpej Exp */
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/*-
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* Copyright (c) 1996, 1997, 1999, 2000 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
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* NASA Ames Research Center.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Copyright (c) 1982, 1986, 1988, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)ufs_disksubr.c 8.5 (Berkeley) 1/21/94
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: bufq_readprio.c,v 1.11 2008/04/30 12:09:02 reinoud Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/buf.h>
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#include <sys/bufq.h>
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#include <sys/bufq_impl.h>
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#include <sys/malloc.h>
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/*
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* Seek sort for disks.
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*
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* There are two queues. The first queue holds read requests; the second
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* holds write requests. The read queue is first-come first-served; the
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* write queue is sorted in ascendening block order.
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* The read queue is processed first. After PRIO_READ_BURST consecutive
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* read requests with non-empty write queue PRIO_WRITE_REQ requests from
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* the write queue will be processed.
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*/
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#define PRIO_READ_BURST 48
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#define PRIO_WRITE_REQ 16
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struct bufq_prio {
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TAILQ_HEAD(, buf) bq_read, bq_write; /* actual list of buffers */
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struct buf *bq_write_next; /* next request in bq_write */
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struct buf *bq_next; /* current request */
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int bq_read_burst; /* # of consecutive reads */
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};
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static void bufq_readprio_init(struct bufq_state *);
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static void bufq_prio_put(struct bufq_state *, struct buf *);
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static struct buf *bufq_prio_get(struct bufq_state *, int);
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BUFQ_DEFINE(readprio, 30, bufq_readprio_init);
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static void
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bufq_prio_put(struct bufq_state *bufq, struct buf *bp)
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{
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struct bufq_prio *prio = bufq->bq_private;
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struct buf *bq;
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int sortby;
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sortby = bufq->bq_flags & BUFQ_SORT_MASK;
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/*
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* If it's a read request append it to the list.
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*/
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if ((bp->b_flags & B_READ) == B_READ) {
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TAILQ_INSERT_TAIL(&prio->bq_read, bp, b_actq);
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return;
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}
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bq = TAILQ_FIRST(&prio->bq_write);
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/*
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* If the write list is empty, simply append it to the list.
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*/
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if (bq == NULL) {
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TAILQ_INSERT_TAIL(&prio->bq_write, bp, b_actq);
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prio->bq_write_next = bp;
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return;
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}
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/*
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* If we lie after the next request, insert after this request.
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*/
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if (buf_inorder(prio->bq_write_next, bp, sortby))
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bq = prio->bq_write_next;
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/*
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* Search for the first request at a larger block number.
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* We go before this request if it exists.
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*/
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while (bq != NULL && buf_inorder(bq, bp, sortby))
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bq = TAILQ_NEXT(bq, b_actq);
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if (bq != NULL)
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TAILQ_INSERT_BEFORE(bq, bp, b_actq);
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else
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TAILQ_INSERT_TAIL(&prio->bq_write, bp, b_actq);
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}
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static struct buf *
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bufq_prio_get(struct bufq_state *bufq, int remove)
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{
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struct bufq_prio *prio = bufq->bq_private;
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struct buf *bp;
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/*
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* If no current request, get next from the lists.
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*/
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if (prio->bq_next == NULL) {
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/*
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* If at least one list is empty, select the other.
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*/
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if (TAILQ_FIRST(&prio->bq_read) == NULL) {
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prio->bq_next = prio->bq_write_next;
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prio->bq_read_burst = 0;
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} else if (prio->bq_write_next == NULL) {
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bp = prio->bq_next = TAILQ_FIRST(&prio->bq_read);
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prio->bq_read_burst = 0;
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KASSERT((bp == NULL) ||
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((bp->b_flags & B_READ) == B_READ));
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} else {
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/*
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* Both list have requests. Select the read list up
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* to PRIO_READ_BURST times, then select the write
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* list PRIO_WRITE_REQ times.
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*/
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if (prio->bq_read_burst++ < PRIO_READ_BURST)
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prio->bq_next = TAILQ_FIRST(&prio->bq_read);
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else if (prio->bq_read_burst <
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PRIO_READ_BURST + PRIO_WRITE_REQ)
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prio->bq_next = prio->bq_write_next;
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else {
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prio->bq_next = TAILQ_FIRST(&prio->bq_read);
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prio->bq_read_burst = 0;
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}
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}
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}
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bp = prio->bq_next;
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if (bp != NULL && remove) {
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if ((bp->b_flags & B_READ) == B_READ)
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TAILQ_REMOVE(&prio->bq_read, bp, b_actq);
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else {
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/*
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* Advance the write pointer before removing
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* bp since it is actually prio->bq_write_next.
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*/
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prio->bq_write_next =
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TAILQ_NEXT(prio->bq_write_next, b_actq);
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TAILQ_REMOVE(&prio->bq_write, bp, b_actq);
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if (prio->bq_write_next == NULL)
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prio->bq_write_next =
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TAILQ_FIRST(&prio->bq_write);
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}
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prio->bq_next = NULL;
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}
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return (bp);
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}
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static struct buf *
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bufq_prio_cancel(struct bufq_state *bufq, struct buf *buf)
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{
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struct bufq_prio *prio = bufq->bq_private;
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struct buf *bq;
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/* search read queue */
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bq = TAILQ_FIRST(&prio->bq_read);
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while (bq) {
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if (bq == buf) {
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TAILQ_REMOVE(&prio->bq_read, bq, b_actq);
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/* force new section */
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prio->bq_next = NULL;
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return buf;
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}
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bq = TAILQ_NEXT(bq, b_actq);
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}
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/* not found in read queue, search write queue */
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bq = TAILQ_FIRST(&prio->bq_write);
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while (bq) {
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if (bq == buf) {
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if (bq == prio->bq_write_next) {
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/*
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* Advance the write pointer before removing
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* bp since it is actually prio->bq_write_next.
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*/
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prio->bq_write_next =
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TAILQ_NEXT(prio->bq_write_next, b_actq);
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TAILQ_REMOVE(&prio->bq_write, bq, b_actq);
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if (prio->bq_write_next == NULL)
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prio->bq_write_next =
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TAILQ_FIRST(&prio->bq_write);
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} else {
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TAILQ_REMOVE(&prio->bq_write, bq, b_actq);
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}
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/* force new section */
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prio->bq_next = NULL;
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return buf;
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}
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bq = TAILQ_NEXT(bq, b_actq);
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}
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/* still not found */
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return NULL;
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}
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static void
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bufq_readprio_init(struct bufq_state *bufq)
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{
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struct bufq_prio *prio;
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bufq->bq_get = bufq_prio_get;
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bufq->bq_put = bufq_prio_put;
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bufq->bq_cancel = bufq_prio_cancel;
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bufq->bq_private = malloc(sizeof(struct bufq_prio), M_DEVBUF, M_ZERO);
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prio = (struct bufq_prio *)bufq->bq_private;
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TAILQ_INIT(&prio->bq_read);
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TAILQ_INIT(&prio->bq_write);
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}
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