minix/servers/vm/cache.c

   1
   2 /* File that implements the data structure, insert, lookup and remove
   3  * functions for file system cache blocks.
   4  *
   5  * Cache blocks can be mapped into the memory of processes by the
   6  * 'cache' and 'file' memory types.
   7  */
   8
   9 #include <assert.h>
  10 #include <string.h>
  11
  12 #include <minix/hash.h>
  13
  14 #include "proto.h"
  15 #include "vm.h"
  16 #include "region.h"
  17 #include "glo.h"
  18 #include "cache.h"
  19
  20 /* cache datastructure */
  21 #define HASHSIZE 65536
  22
  23 static struct cached_page *cache_hash_bydev[HASHSIZE];
  24 static struct cached_page *cache_hash_byino[HASHSIZE];
  25 static struct cached_page *lru_oldest = NULL, *lru_newest = NULL;
  26
  27 static u32_t cached_pages = 0;
  28
  29 static void lru_rm(struct cached_page *hb)
  30 {
  31         struct cached_page *newer = hb->newer, *older = hb->older;
  32         assert(lru_newest);
  33         assert(lru_oldest);
  34         if(newer) {
  35                 assert(newer->older == hb);
  36                 newer->older = older;
  37         }
  38         if(older) {
  39                 assert(older->newer == hb);
  40                 older->newer = newer;
  41         }
  42
  43         if(lru_newest == hb) { assert(!newer); lru_newest = older; }
  44         if(lru_oldest == hb) { assert(!older); lru_oldest = newer; }
  45
  46         if(lru_newest) assert(lru_newest->newer == NULL);
  47         if(lru_oldest) assert(lru_oldest->older == NULL);
  48
  49         cached_pages--;
  50 }
  51
  52 static void lru_add(struct cached_page *hb)
  53 {
  54         if(lru_newest) {
  55                 assert(lru_oldest);
  56                 assert(!lru_newest->newer);
  57                 lru_newest->newer = hb;
  58         } else {
  59                 assert(!lru_oldest);
  60                 lru_oldest = hb;
  61         }
  62
  63         hb->older = lru_newest;
  64         hb->newer = NULL;
  65         lru_newest = hb;
  66
  67         cached_pages++;
  68 }
  69
  70 void cache_lru_touch(struct cached_page *hb)
  71 {
  72         lru_rm(hb);
  73         lru_add(hb);
  74 }
  75
  76 static __inline u32_t makehash(u32_t p1, u64_t p2)
  77 {
  78         u32_t offlo = ex64lo(p2), offhi = ex64hi(p2),
  79                 v = 0x12345678;
  80         hash_mix(p1, offlo, offhi);
  81         hash_final(offlo, offhi, v);
  82
  83         return v % HASHSIZE;
  84 }
  85
  86 #if CACHE_SANITY
  87 void cache_sanitycheck_internal(void)
  88 {
  89         int h;
  90         int n = 0;
  91         int byino = 0;
  92         int withino = 0;
  93         int bydev_total = 0, lru_total = 0;
  94         struct cached_page *cp;
  95
  96         for(h = 0; h < HASHSIZE; h++) {
  97                 for(cp = cache_hash_bydev[h]; cp; cp = cp->hash_next_dev) {
  98                         assert(cp->dev != NO_DEV);
  99                         assert(h == makehash(cp->dev, cp->dev_offset));
 100                         assert(cp == find_cached_page_bydev(cp->dev, cp->dev_offset, cp->ino, cp->ino_offset));
 101                         if(cp->ino != VMC_NO_INODE) withino++;
 102                         bydev_total++;
 103                         n++;
 104                         assert(n < 1500000);
 105                 }
 106                 for(cp = cache_hash_byino[h]; cp; cp = cp->hash_next_ino) {
 107                         assert(cp->dev != NO_DEV);
 108                         assert(cp->ino != VMC_NO_INODE);
 109                         assert(h == makehash(cp->ino, cp->ino_offset));
 110                         byino++;
 111                         n++;
 112                         assert(n < 1500000);
 113                 }
 114         }
 115
 116         assert(byino == withino);
 117
 118         if(lru_newest) {
 119                 assert(lru_oldest);
 120                 assert(!lru_newest->newer);
 121                 assert(!lru_oldest->older);
 122         } else {
 123                 assert(!lru_oldest);
 124         }
 125
 126         for(cp = lru_oldest; cp; cp = cp->newer) {
 127                 struct cached_page *newer = cp->newer,
 128                         *older = cp->older;
 129                 if(newer) assert(newer->older == cp);
 130                 if(older) assert(older->newer == cp);
 131                 lru_total++;
 132         }
 133
 134         assert(lru_total == bydev_total);
 135
 136         assert(lru_total == cached_pages);
 137 }
 138 #endif
 139
 140 #define rmhash_f(fname, nextfield)                      \
 141 static void                                             \
 142 fname(struct cached_page *cp, struct cached_page **head)        \
 143 {                                                               \
 144         struct cached_page *hb;                                 \
 145         if(*head == cp) { *head = cp->nextfield; return; }                      \
 146         for(hb = *head; hb && cp != hb->nextfield; hb = hb->nextfield) ; \
 147         assert(hb); assert(hb->nextfield == cp);                \
 148         hb->nextfield = cp->nextfield;          \
 149         return;                                 \
 150 }
 151
 152 rmhash_f(rmhash_byino, hash_next_ino)
 153 rmhash_f(rmhash_bydev, hash_next_dev)
 154
 155 static void addcache_byino(struct cached_page *hb)
 156 {
 157         int hv_ino = makehash(hb->ino, hb->ino_offset);
 158         assert(hb->ino != VMC_NO_INODE);
 159         hb->hash_next_ino = cache_hash_byino[hv_ino];
 160         cache_hash_byino[hv_ino] = hb;
 161 }
 162
 163 static void
 164 update_inohash(struct cached_page *hb, ino_t ino, u64_t ino_off)
 165 {
 166         assert(ino != VMC_NO_INODE);
 167         if(hb->ino != VMC_NO_INODE) {
 168                 int h = makehash(hb->ino, hb->ino_offset);
 169                 rmhash_byino(hb, &cache_hash_byino[h]);
 170         }
 171         hb->ino = ino;
 172         hb->ino_offset = ino_off;
 173         addcache_byino(hb);
 174 }
 175
 176 struct cached_page *
 177 find_cached_page_bydev(dev_t dev, u64_t dev_off, ino_t ino, u64_t ino_off, int touchlru)
 178 {
 179         struct cached_page *hb;
 180
 181         for(hb = cache_hash_bydev[makehash(dev, dev_off)]; hb; hb=hb->hash_next_dev) {
 182                 if(hb->dev == dev && hb->dev_offset == dev_off) {
 183                         if(ino != VMC_NO_INODE) {
 184                                 if(hb->ino != ino || hb->ino_offset != ino_off) {
 185                                         update_inohash(hb, ino, ino_off);
 186                                 }
 187                         }
 188
 189                         if(touchlru) cache_lru_touch(hb);
 190
 191                         return hb;
 192                 }
 193         }
 194
 195         return NULL;
 196 }
 197
 198 struct cached_page *find_cached_page_byino(dev_t dev, ino_t ino, u64_t ino_off, int touchlru)
 199 {
 200         struct cached_page *hb;
 201
 202         assert(ino != VMC_NO_INODE);
 203         assert(dev != NO_DEV);
 204
 205         for(hb = cache_hash_byino[makehash(ino, ino_off)]; hb; hb=hb->hash_next_ino) {
 206                 if(hb->dev == dev && hb->ino == ino && hb->ino_offset == ino_off) {
 207                         if(touchlru) cache_lru_touch(hb);
 208
 209                         return hb;
 210                 }
 211         }
 212
 213         return NULL;
 214 }
 215
 216 int addcache(dev_t dev, u64_t dev_off, ino_t ino, u64_t ino_off, int flags,
 217         struct phys_block *pb)
 218 {
 219         int hv_dev;
 220         struct cached_page *hb;
 221
 222         if(pb->flags & PBF_INCACHE) {
 223                 printf("VM: already in cache\n");
 224                 return EINVAL;
 225         }
 226
 227         if(!SLABALLOC(hb)) {
 228                 printf("VM: no memory for cache node\n");
 229                 return ENOMEM;
 230         }
 231
 232         assert(dev != NO_DEV);
 233 #if CACHE_SANITY
 234         assert(!find_cached_page_bydev(dev, dev_off, ino, ino_off));
 235 #endif
 236
 237         hb->dev = dev;
 238         hb->dev_offset = dev_off;
 239         hb->ino = ino;
 240         hb->ino_offset = ino_off;
 241         hb->flags = flags & VMSF_ONCE;
 242         hb->page = pb;
 243         hb->page->refcount++;   /* block also referenced by cache now */
 244         hb->page->flags |= PBF_INCACHE;
 245
 246         hv_dev = makehash(dev, dev_off);
 247
 248         hb->hash_next_dev = cache_hash_bydev[hv_dev];
 249         cache_hash_bydev[hv_dev] = hb;
 250
 251         if(hb->ino != VMC_NO_INODE)
 252                 addcache_byino(hb);
 253
 254         lru_add(hb);
 255
 256         return OK;
 257 }
 258
 259 void rmcache(struct cached_page *cp)
 260 {
 261         struct phys_block *pb = cp->page;
 262         int hv_dev = makehash(cp->dev, cp->dev_offset);
 263
 264         assert(cp->page->flags & PBF_INCACHE);
 265
 266         cp->page->flags &= ~PBF_INCACHE;
 267
 268         rmhash_bydev(cp, &cache_hash_bydev[hv_dev]);
 269         if(cp->ino != VMC_NO_INODE) {
 270                 int hv_ino = makehash(cp->ino, cp->ino_offset);
 271                 rmhash_byino(cp, &cache_hash_byino[hv_ino]);
 272         }
 273
 274         assert(cp->page->refcount >= 1);
 275         cp->page->refcount--;
 276
 277         lru_rm(cp);
 278
 279         if(pb->refcount == 0) {
 280                 assert(pb->phys != MAP_NONE);
 281                 free_mem(ABS2CLICK(pb->phys), 1);
 282                 SLABFREE(pb);
 283         }
 284
 285         SLABFREE(cp);
 286 }
 287
 288 int cache_freepages(int pages)
 289 {
 290         struct cached_page *cp, *newercp;
 291         int freed = 0;
 292         int oldsteps = 0;
 293         int skips = 0;
 294
 295         for(cp = lru_oldest; cp && freed < pages; cp = newercp) {
 296                 newercp = cp->newer;
 297                 assert(cp->page->refcount >= 1);
 298                 if(cp->page->refcount == 1) {
 299                         rmcache(cp);
 300                         freed++;
 301                         skips = 0;
 302                 } else skips++;
 303                 oldsteps++;
 304         }
 305
 306         return freed;
 307 }
 308
 309 /*
 310  * Remove all pages that are associated with the given device.
 311  */
 312 void
 313 clear_cache_bydev(dev_t dev)
 314 {
 315         struct cached_page *cp, *ncp;
 316         int h;
 317
 318         for (h = 0; h < HASHSIZE; h++) {
 319                 for (cp = cache_hash_bydev[h]; cp != NULL; cp = ncp) {
 320                         ncp = cp->hash_next_dev;
 321
 322                         if (cp->dev == dev)
 323                                 rmcache(cp);
 324                 }
 325         }
 326 }
 327
 328 void get_stats_info(struct vm_stats_info *vsi)
 329 {
 330         vsi->vsi_cached = cached_pages;
 331 }
 332