1/*-
2 * Copyright (c) 2009-2010 Fabio Checconi
3 * Copyright (c) 2009-2010 Luigi Rizzo, Universita` di Pisa
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#ifndef	_G_SCHED_H_
29#define	_G_SCHED_H_
30
31/*
32 * $Id$
33 * $FreeBSD$
34 *
35 * Header for the geom_sched class (userland library and kernel part).
36 * See g_sched.c for documentation.
37 * The userland code only needs the three G_SCHED_* values below.
38 */
39
40#define	G_SCHED_CLASS_NAME	"SCHED"
41#define	G_SCHED_VERSION		0
42#define	G_SCHED_SUFFIX		".sched."
43
44#ifdef _KERNEL
45#define	G_SCHED_DEBUG(lvl, ...)	do {				\
46	if (me.gs_debug >= (lvl)) {				\
47		printf("GEOM_SCHED");				\
48		if (me.gs_debug > 0)				\
49			printf("[%u]", lvl);			\
50		printf(": ");					\
51		printf(__VA_ARGS__);				\
52		printf("\n");					\
53	}							\
54} while (0)
55
56#define	G_SCHED_LOGREQ(bp, ...)	do {				\
57	if (me.gs_debug >= 2) {					\
58		printf("GEOM_SCHED[2]: ");			\
59		printf(__VA_ARGS__);				\
60		printf(" ");					\
61		g_print_bio(bp);				\
62		printf("\n");					\
63	}							\
64} while (0)
65
66LIST_HEAD(g_hash, g_sched_class);
67
68/*
69 * Descriptor of a scheduler.
70 * In addition to the obvious fields, sc_flushing and sc_pending
71 * support dynamic switching of scheduling algorithm.
72 * Normally, sc_flushing is 0, and requests that are scheduled are
73 * also added to the sc_pending queue, and removed when we receive
74 * the 'done' event.
75 *
76 * When we are transparently inserted on an existing provider,
77 * sc_proxying is set. The detach procedure is slightly different.
78 *
79 * When switching schedulers, sc_flushing is set so requests bypass us,
80 * and at the same time we update the pointer in the pending bios
81 * to ignore us when they return up.
82 * XXX it would be more efficient to implement sc_pending with
83 * a generation number: the softc generation is increased when
84 * we change scheduling algorithm, we store the current generation
85 * number in the pending bios, and when they come back we ignore
86 * the done() call if the generation number do not match.
87 */
88struct g_sched_softc {
89	/*
90	 * Generic fields used by any scheduling algorithm:
91	 * a mutex, the class descriptor, flags, list of pending
92	 * requests (used when flushing the module) and support
93	 * for hash tables where we store per-flow queues.
94	 */
95	struct mtx	sc_mtx;
96	struct g_gsched	*sc_gsched;	/* Scheduler descriptor. */
97	int		sc_pending;	/* Pending requests. */
98	int		sc_flags;	/* Various flags. */
99
100	/*
101	 * Hash tables to store per-flow queues are generally useful
102	 * so we handle them in the common code.
103	 * sc_hash and sc_mask are parameters of the hash table,
104	 * the last two fields are used to periodically remove
105	 * expired items from the hash table.
106	 */
107	struct g_hash	*sc_hash;
108	u_long		sc_mask;
109	int		sc_flush_ticks;	/* Next tick for a flush. */
110	int		sc_flush_bucket; /* Next bucket to flush. */
111
112	/*
113	 * Pointer to the algorithm's private data, which is the value
114	 * returned by sc_gsched->gs_init() . A NULL here means failure.
115	 * XXX intptr_t might be more appropriate.
116	 */
117	void		*sc_data;
118};
119
120#define	G_SCHED_PROXYING	1
121#define	G_SCHED_FLUSHING	2
122
123/*
124 * Temporary- our own version of the disksort, because the
125 * version in 7.x and 8.x before march 2009 is buggy.
126 */
127void gs_bioq_init(struct bio_queue_head *);
128void gs_bioq_remove(struct bio_queue_head *, struct bio *);
129void gs_bioq_flush(struct bio_queue_head *, struct devstat *, int);
130void gs_bioq_insert_head(struct bio_queue_head *, struct bio *);
131void gs_bioq_insert_tail(struct bio_queue_head *, struct bio *);
132struct bio *gs_bioq_first(struct bio_queue_head *);
133struct bio *gs_bioq_takefirst(struct bio_queue_head *);
134void gs_bioq_disksort(struct bio_queue_head *, struct bio *);
135
136#endif	/* _KERNEL */
137
138#endif	/* _G_SCHED_H_ */
139