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| 2 | pj | 1 | /* |
| 2 | * Project: S.Ha.R.K. |
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| 3 | * |
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| 4 | * Coordinators: |
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| 5 | * Giorgio Buttazzo <giorgio@sssup.it> |
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| 6 | * Paolo Gai <pj@gandalf.sssup.it> |
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| 7 | * |
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| 8 | * Authors : |
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| 9 | * Paolo Gai <pj@gandalf.sssup.it> |
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| 10 | * Massimiliano Giorgi <massy@gandalf.sssup.it> |
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| 11 | * Luca Abeni <luca@gandalf.sssup.it> |
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| 12 | * (see the web pages for full authors list) |
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| 13 | * |
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| 14 | * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy) |
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| 15 | * |
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| 16 | * http://www.sssup.it |
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| 17 | * http://retis.sssup.it |
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| 18 | * http://shark.sssup.it |
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| 19 | */ |
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| 20 | |||
| 21 | /* |
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| 22 | * Copyright (C) 2000 Massimiliano Giorgi |
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| 23 | * |
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| 24 | * This program is free software; you can redistribute it and/or modify |
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| 25 | * it under the terms of the GNU General Public License as published by |
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| 26 | * the Free Software Foundation; either version 2 of the License, or |
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| 27 | * (at your option) any later version. |
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| 28 | * |
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| 29 | * This program is distributed in the hope that it will be useful, |
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| 30 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 31 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 32 | * GNU General Public License for more details. |
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| 33 | * |
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| 34 | * You should have received a copy of the GNU General Public License |
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| 35 | * along with this program; if not, write to the Free Software |
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| 36 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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| 37 | * |
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| 38 | */ |
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| 39 | |||
| 40 | #include "bqueue.h" |
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| 41 | #include "glue.h" |
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| 42 | |||
| 43 | /**/ |
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| 44 | |||
| 45 | #include <modules/bd_pscan.h> |
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| 46 | |||
| 47 | static __inline__ int get_priority(void) |
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| 48 | { |
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| 49 | int x; |
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| 50 | x=bd_pscan_getpriority(); |
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| 51 | if (x<0||x>=NUMPRIORITY) return NUMPRIORITY-1; |
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| 52 | return x; |
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| 53 | } |
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| 54 | |||
| 55 | /**/ |
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| 56 | |||
| 57 | int pscan_init(pscan_queue_t *q) |
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| 58 | { |
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| 59 | int i; |
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| 60 | __b_fastmutex_init(&q->mutex); |
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| 61 | q->disk=NULL; |
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| 62 | q->counter=0; |
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| 63 | q->actprior=0; |
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| 64 | for (i=0;i<NUMPRIORITY;i++) { |
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| 65 | q->pri[i].queue[0]=NULL; |
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| 66 | q->pri[i].queue[1]=NULL; |
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| 67 | q->pri[i].dir=0; |
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| 68 | } |
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| 69 | return 0; |
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| 70 | } |
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| 71 | |||
| 72 | int pscan_numelements(pscan_queue_t *q) |
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| 73 | { |
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| 74 | return q->counter; |
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| 75 | } |
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| 76 | |||
| 77 | /* 0 -> no starvation (low performance) */ |
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| 78 | /* 1 -> possible starvation (high performance) */ |
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| 79 | #define STARVATION 1 |
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| 80 | |||
| 81 | int pscan_insertrequest(pscan_queue_t *q, request_prologue_t *e) |
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| 82 | { |
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| 83 | request_prologue_t *p,*o; |
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| 84 | struct pscan_queues *ptr; |
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| 85 | int i; |
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| 86 | |||
| 87 | __b_fastmutex_lock(&q->mutex); |
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| 88 | |||
| 89 | i=get_priority(); |
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| 90 | ptr=&q->pri[i]; |
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| 91 | |||
| 92 | if (ptr->queue[ptr->dir]==NULL) ptr->dir^=1; |
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| 93 | |||
| 94 | if (ptr->queue[ptr->dir]==NULL) { |
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| 95 | ptr->queue[ptr->dir]=e; |
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| 96 | e->x.next=NULL; |
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| 97 | } else { |
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| 98 | |||
| 99 | if (e->cylinder==ptr->queue[ptr->dir]->cylinder) { |
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| 100 | if (ptr->dir==STARVATION) goto HI_INS; |
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| 101 | else goto LO_INS; |
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| 102 | } |
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| 103 | |||
| 104 | if (e->cylinder<ptr->queue[ptr->dir]->cylinder) { |
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| 105 | LO_INS: |
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| 106 | /* insert into low queue */ |
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| 107 | o=NULL; |
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| 108 | p=ptr->queue[0]; |
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| 109 | while (p!=NULL) { |
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| 110 | if (e->cylinder>p->cylinder) break; |
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| 111 | o=p; |
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| 112 | p=p->x.next; |
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| 113 | } |
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| 114 | if (o==NULL) ptr->queue[0]=e; |
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| 115 | else o->x.next=e; |
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| 116 | e->x.next=p; |
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| 117 | } else { |
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| 118 | HI_INS: |
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| 119 | /* insert into high queue */ |
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| 120 | o=NULL; |
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| 121 | p=ptr->queue[1]; |
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| 122 | while (p!=NULL) { |
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| 123 | if (e->cylinder<p->cylinder) break; |
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| 124 | o=p; |
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| 125 | p=p->x.next; |
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| 126 | } |
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| 127 | if (o==NULL) ptr->queue[1]=e; |
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| 128 | else o->x.next=e; |
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| 129 | e->x.next=p; |
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| 130 | } |
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| 131 | |||
| 132 | } |
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| 133 | |||
| 134 | q->counter++; |
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| 135 | __b_fastmutex_unlock(&q->mutex); |
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| 136 | return 0; |
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| 137 | } |
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| 138 | |||
| 139 | request_prologue_t *pscan_getrequest(pscan_queue_t *q) |
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| 140 | { |
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| 141 | request_prologue_t *ret; |
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| 142 | int i; |
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| 143 | __b_fastmutex_lock(&q->mutex); |
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| 144 | for (i=0;i<NUMPRIORITY;i++) { |
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| 145 | q->actprior=i; |
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| 146 | ret=q->pri[i].queue[q->pri[i].dir]; |
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| 147 | if (ret!=NULL) break; |
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| 148 | else { |
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| 149 | q->pri[i].dir^=1; |
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| 150 | ret=q->pri[i].queue[q->pri[i].dir]; |
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| 151 | if (ret!=NULL) break; |
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| 152 | } |
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| 153 | } |
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| 154 | //cprintf("{%i}",i); |
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| 155 | __b_fastmutex_lock(&q->mutex); |
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| 156 | return ret; |
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| 157 | } |
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| 158 | |||
| 159 | int pscan_removerequest(pscan_queue_t *q) |
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| 160 | { |
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| 161 | struct pscan_queues *ptr; |
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| 162 | __b_fastmutex_lock(&q->mutex); |
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| 163 | ptr=&q->pri[q->actprior]; |
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| 164 | assertk(ptr->queue[ptr->dir]!=NULL); |
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| 165 | ptr->queue[ptr->dir]=ptr->queue[ptr->dir]->x.next; |
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| 166 | q->counter--; |
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| 167 | __b_fastmutex_unlock(&q->mutex); |
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| 168 | return 0; |
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| 169 | } |