g_sched.h

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    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: releng/8.3/sys/geom/sched/g_sched.h 206899 2010-04-20 15:23:12Z luigi $
   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 
   66 LIST_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  */
   88 struct 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  */
  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 *);
  135 
  136 #endif  /* _KERNEL */
  137 
  138 #endif  /* _G_SCHED_H_ */

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FreeBSD/Linux Kernel Cross Reference sys/geom/sched/g_sched.h

FreeBSD/Linux Kernel Cross Reference
sys/geom/sched/g_sched.h