2 * Copyright (c) 2009-2010 Fabio Checconi
3 * Copyright (c) 2009-2010 Luigi Rizzo, Universita` di Pisa
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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.
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
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.
40 #define G_SCHED_CLASS_NAME "SCHED"
41 #define G_SCHED_VERSION 0
42 #define G_SCHED_SUFFIX ".sched."
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); \
51 printf(__VA_ARGS__); \
56 #define G_SCHED_LOGREQ(bp, ...) do { \
57 if (me.gs_debug >= 2) { \
58 printf("GEOM_SCHED[2]: "); \
59 printf(__VA_ARGS__); \
66 LIST_HEAD(g_hash, g_sched_class);
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
76 * When we are transparently inserted on an existing provider,
77 * sc_proxying is set. The detach procedure is slightly different.
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.
88 struct g_sched_softc {
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.
96 struct g_gsched *sc_gsched; /* Scheduler descriptor. */
97 int sc_pending; /* Pending requests. */
98 int sc_flags; /* Various flags. */
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.
107 struct g_hash *sc_hash;
109 int sc_flush_ticks; /* Next tick for a flush. */
110 int sc_flush_bucket; /* Next bucket to flush. */
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.
120 #define G_SCHED_PROXYING 1
121 #define G_SCHED_FLUSHING 2
124 * Temporary- our own version of the disksort, because the
125 * version in 7.x and 8.x before march 2009 is buggy.
127 void gs_bioq_init(struct bio_queue_head *);
128 void gs_bioq_remove(struct bio_queue_head *, struct bio *);
129 void gs_bioq_flush(struct bio_queue_head *, struct devstat *, int);
130 void gs_bioq_insert_head(struct bio_queue_head *, struct bio *);
131 void gs_bioq_insert_tail(struct bio_queue_head *, struct bio *);
132 struct bio *gs_bioq_first(struct bio_queue_head *);
133 struct bio *gs_bioq_takefirst(struct bio_queue_head *);
134 void gs_bioq_disksort(struct bio_queue_head *, struct bio *);
138 #endif /* _G_SCHED_H_ */