sys/kern/kern_iosched.c

   1 /*
   2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/param.h>
  36 #include <sys/systm.h>
  37 #include <sys/kernel.h>
  38 #include <sys/proc.h>
  39 #include <sys/rtprio.h>
  40 #include <sys/queue.h>
  41 #include <machine/cpu.h>
  42 #include <sys/spinlock.h>
  43 #include <sys/iosched.h>
  44 #include <sys/sysctl.h>
  45 #include <sys/buf.h>
  46 #include <sys/limits.h>
  47
  48 #include <sys/spinlock2.h>
  49
  50 #include <vm/vm.h>
  51 #include <vm/vm_param.h>
  52 #include <vm/vm_kern.h>
  53 #include <vm/vm_extern.h>
  54
  55 SYSCTL_NODE(, OID_AUTO, iosched, CTLFLAG_RW, 0, "I/O Scheduler");
  56
  57 static int iosched_debug = 0;
  58 SYSCTL_INT(_iosched, OID_AUTO, debug, CTLFLAG_RW, &iosched_debug, 0, "");
  59
  60 static struct iosched_data      ioscpu[SMP_MAXCPU];
  61
  62 /*
  63  * MPSAFE
  64  */
  65 static int
  66 badjiosched(thread_t td, size_t bytes)
  67 {
  68         globaldata_t gd = mycpu;
  69         size_t iostotal;
  70         int factor;
  71         int i;
  72         int delta;
  73
  74         iostotal = 0;
  75         for (i = 0; i < ncpus; ++i)
  76                 iostotal += ioscpu[i].iowbytes;
  77         if (SIZE_T_MAX / SMP_MAXCPU - td->td_iosdata.iowbytes < bytes)
  78                 bytes = SIZE_T_MAX / SMP_MAXCPU - td->td_iosdata.iowbytes;
  79         td->td_iosdata.iowbytes += bytes;
  80         ioscpu[gd->gd_cpuid].iowbytes += bytes;
  81         iostotal += bytes;
  82         delta = ticks - td->td_iosdata.lastticks;
  83         if (delta) {
  84                 td->td_iosdata.lastticks = ticks;
  85                 if (delta < 0 || delta > hz * 10)
  86                         delta = hz * 10;
  87                 /* be careful of interger overflows */
  88                 bytes = (int64_t)td->td_iosdata.iowbytes * delta / (hz * 10);
  89                 td->td_iosdata.iowbytes -= bytes;
  90                 ioscpu[gd->gd_cpuid].iowbytes -= bytes;
  91                 iostotal -= bytes;
  92         }
  93
  94         /* be careful of interger overflows */
  95         if (iostotal > 0)
  96                 factor = (int64_t)td->td_iosdata.iowbytes * 100 / iostotal;
  97         else
  98                 factor = 50;
  99
 100         if (delta && (iosched_debug & 1)) {
 101                 kprintf("proc %12s (%-5d) factor %3d (%zd/%zd)\n",
 102                         td->td_comm,
 103                         (td->td_lwp ? (int)td->td_lwp->lwp_proc->p_pid : -1),
 104                         factor, td->td_iosdata.iowbytes, iostotal);
 105         }
 106         return (factor);
 107 }
 108
 109 void
 110 biosched_done(thread_t td)
 111 {
 112         globaldata_t gd = mycpu;
 113         size_t bytes;
 114
 115         if ((bytes = td->td_iosdata.iowbytes) != 0) {
 116                 td->td_iosdata.iowbytes = 0;
 117                 ioscpu[gd->gd_cpuid].iowbytes -= bytes;
 118         }
 119 }
 120
 121 /*
 122  * Caller intends to write (bytes)
 123  *
 124  * MPSAFE
 125  */
 126 void
 127 bwillwrite(int bytes)
 128 {
 129         long count;
 130         long factor;
 131
 132         count = bd_heatup();
 133         if (count > 0) {
 134                 /* be careful of interger overflows */
 135                 factor = badjiosched(curthread, (size_t)bytes);
 136                 count = hidirtybufspace / 100 * factor;
 137                 bd_wait(count);
 138         }
 139 }
 140
 141 /*
 142  * Caller intends to read (bytes)
 143  *
 144  * MPSAFE
 145  */
 146 void
 147 bwillread(int bytes)
 148 {
 149 }
 150
 151 /*
 152  * Call intends to do an inode-modifying operation of some sort.
 153  *
 154  * MPSAFE
 155  */
 156 void
 157 bwillinode(int n)
 158 {
 159         long count;
 160         long factor;
 161
 162         count = bd_heatup();
 163         if (count > 0) {
 164                 factor = badjiosched(curthread, PAGE_SIZE);
 165                 count = count * factor / 100;
 166                 bd_wait(count);
 167         }
 168 }
 169