Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Primary bucket allocation code |
| 3 | * |
| 4 | * Copyright 2012 Google, Inc. |
| 5 | * |
| 6 | * Allocation in bcache is done in terms of buckets: |
| 7 | * |
| 8 | * Each bucket has associated an 8 bit gen; this gen corresponds to the gen in |
| 9 | * btree pointers - they must match for the pointer to be considered valid. |
| 10 | * |
| 11 | * Thus (assuming a bucket has no dirty data or metadata in it) we can reuse a |
| 12 | * bucket simply by incrementing its gen. |
| 13 | * |
| 14 | * The gens (along with the priorities; it's really the gens are important but |
| 15 | * the code is named as if it's the priorities) are written in an arbitrary list |
| 16 | * of buckets on disk, with a pointer to them in the journal header. |
| 17 | * |
| 18 | * When we invalidate a bucket, we have to write its new gen to disk and wait |
| 19 | * for that write to complete before we use it - otherwise after a crash we |
| 20 | * could have pointers that appeared to be good but pointed to data that had |
| 21 | * been overwritten. |
| 22 | * |
| 23 | * Since the gens and priorities are all stored contiguously on disk, we can |
| 24 | * batch this up: We fill up the free_inc list with freshly invalidated buckets, |
| 25 | * call prio_write(), and when prio_write() finishes we pull buckets off the |
| 26 | * free_inc list and optionally discard them. |
| 27 | * |
| 28 | * free_inc isn't the only freelist - if it was, we'd often to sleep while |
| 29 | * priorities and gens were being written before we could allocate. c->free is a |
| 30 | * smaller freelist, and buckets on that list are always ready to be used. |
| 31 | * |
| 32 | * If we've got discards enabled, that happens when a bucket moves from the |
| 33 | * free_inc list to the free list. |
| 34 | * |
| 35 | * There is another freelist, because sometimes we have buckets that we know |
| 36 | * have nothing pointing into them - these we can reuse without waiting for |
| 37 | * priorities to be rewritten. These come from freed btree nodes and buckets |
| 38 | * that garbage collection discovered no longer had valid keys pointing into |
| 39 | * them (because they were overwritten). That's the unused list - buckets on the |
| 40 | * unused list move to the free list, optionally being discarded in the process. |
| 41 | * |
| 42 | * It's also important to ensure that gens don't wrap around - with respect to |
| 43 | * either the oldest gen in the btree or the gen on disk. This is quite |
| 44 | * difficult to do in practice, but we explicitly guard against it anyways - if |
| 45 | * a bucket is in danger of wrapping around we simply skip invalidating it that |
| 46 | * time around, and we garbage collect or rewrite the priorities sooner than we |
| 47 | * would have otherwise. |
| 48 | * |
| 49 | * bch_bucket_alloc() allocates a single bucket from a specific cache. |
| 50 | * |
| 51 | * bch_bucket_alloc_set() allocates one or more buckets from different caches |
| 52 | * out of a cache set. |
| 53 | * |
| 54 | * free_some_buckets() drives all the processes described above. It's called |
| 55 | * from bch_bucket_alloc() and a few other places that need to make sure free |
| 56 | * buckets are ready. |
| 57 | * |
| 58 | * invalidate_buckets_(lru|fifo)() find buckets that are available to be |
| 59 | * invalidated, and then invalidate them and stick them on the free_inc list - |
| 60 | * in either lru or fifo order. |
| 61 | */ |
| 62 | |
| 63 | #include "bcache.h" |
| 64 | #include "btree.h" |
| 65 | |
Kent Overstreet | 49b1212 | 2013-07-24 17:16:09 -0700 | [diff] [blame] | 66 | #include <linux/blkdev.h> |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 67 | #include <linux/freezer.h> |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 68 | #include <linux/kthread.h> |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 69 | #include <linux/random.h> |
Kent Overstreet | c37511b | 2013-04-26 15:39:55 -0700 | [diff] [blame] | 70 | #include <trace/events/bcache.h> |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 71 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 72 | /* Bucket heap / gen */ |
| 73 | |
| 74 | uint8_t bch_inc_gen(struct cache *ca, struct bucket *b) |
| 75 | { |
| 76 | uint8_t ret = ++b->gen; |
| 77 | |
| 78 | ca->set->need_gc = max(ca->set->need_gc, bucket_gc_gen(b)); |
| 79 | WARN_ON_ONCE(ca->set->need_gc > BUCKET_GC_GEN_MAX); |
| 80 | |
| 81 | if (CACHE_SYNC(&ca->set->sb)) { |
| 82 | ca->need_save_prio = max(ca->need_save_prio, |
| 83 | bucket_disk_gen(b)); |
| 84 | WARN_ON_ONCE(ca->need_save_prio > BUCKET_DISK_GEN_MAX); |
| 85 | } |
| 86 | |
| 87 | return ret; |
| 88 | } |
| 89 | |
| 90 | void bch_rescale_priorities(struct cache_set *c, int sectors) |
| 91 | { |
| 92 | struct cache *ca; |
| 93 | struct bucket *b; |
| 94 | unsigned next = c->nbuckets * c->sb.bucket_size / 1024; |
| 95 | unsigned i; |
| 96 | int r; |
| 97 | |
| 98 | atomic_sub(sectors, &c->rescale); |
| 99 | |
| 100 | do { |
| 101 | r = atomic_read(&c->rescale); |
| 102 | |
| 103 | if (r >= 0) |
| 104 | return; |
| 105 | } while (atomic_cmpxchg(&c->rescale, r, r + next) != r); |
| 106 | |
| 107 | mutex_lock(&c->bucket_lock); |
| 108 | |
| 109 | c->min_prio = USHRT_MAX; |
| 110 | |
| 111 | for_each_cache(ca, c, i) |
| 112 | for_each_bucket(b, ca) |
| 113 | if (b->prio && |
| 114 | b->prio != BTREE_PRIO && |
| 115 | !atomic_read(&b->pin)) { |
| 116 | b->prio--; |
| 117 | c->min_prio = min(c->min_prio, b->prio); |
| 118 | } |
| 119 | |
| 120 | mutex_unlock(&c->bucket_lock); |
| 121 | } |
| 122 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 123 | /* Allocation */ |
| 124 | |
| 125 | static inline bool can_inc_bucket_gen(struct bucket *b) |
| 126 | { |
| 127 | return bucket_gc_gen(b) < BUCKET_GC_GEN_MAX && |
| 128 | bucket_disk_gen(b) < BUCKET_DISK_GEN_MAX; |
| 129 | } |
| 130 | |
| 131 | bool bch_bucket_add_unused(struct cache *ca, struct bucket *b) |
| 132 | { |
| 133 | BUG_ON(GC_MARK(b) || GC_SECTORS_USED(b)); |
| 134 | |
| 135 | if (fifo_used(&ca->free) > ca->watermark[WATERMARK_MOVINGGC] && |
| 136 | CACHE_REPLACEMENT(&ca->sb) == CACHE_REPLACEMENT_FIFO) |
| 137 | return false; |
| 138 | |
| 139 | b->prio = 0; |
| 140 | |
| 141 | if (can_inc_bucket_gen(b) && |
| 142 | fifo_push(&ca->unused, b - ca->buckets)) { |
| 143 | atomic_inc(&b->pin); |
| 144 | return true; |
| 145 | } |
| 146 | |
| 147 | return false; |
| 148 | } |
| 149 | |
| 150 | static bool can_invalidate_bucket(struct cache *ca, struct bucket *b) |
| 151 | { |
| 152 | return GC_MARK(b) == GC_MARK_RECLAIMABLE && |
| 153 | !atomic_read(&b->pin) && |
| 154 | can_inc_bucket_gen(b); |
| 155 | } |
| 156 | |
| 157 | static void invalidate_one_bucket(struct cache *ca, struct bucket *b) |
| 158 | { |
| 159 | bch_inc_gen(ca, b); |
| 160 | b->prio = INITIAL_PRIO; |
| 161 | atomic_inc(&b->pin); |
| 162 | fifo_push(&ca->free_inc, b - ca->buckets); |
| 163 | } |
| 164 | |
Kent Overstreet | b1a67b0 | 2013-03-25 11:46:44 -0700 | [diff] [blame] | 165 | #define bucket_prio(b) \ |
| 166 | (((unsigned) (b->prio - ca->set->min_prio)) * GC_SECTORS_USED(b)) |
| 167 | |
| 168 | #define bucket_max_cmp(l, r) (bucket_prio(l) < bucket_prio(r)) |
| 169 | #define bucket_min_cmp(l, r) (bucket_prio(l) > bucket_prio(r)) |
| 170 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 171 | static void invalidate_buckets_lru(struct cache *ca) |
| 172 | { |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 173 | struct bucket *b; |
| 174 | ssize_t i; |
| 175 | |
| 176 | ca->heap.used = 0; |
| 177 | |
| 178 | for_each_bucket(b, ca) { |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 179 | /* |
| 180 | * If we fill up the unused list, if we then return before |
| 181 | * adding anything to the free_inc list we'll skip writing |
| 182 | * prios/gens and just go back to allocating from the unused |
| 183 | * list: |
| 184 | */ |
| 185 | if (fifo_full(&ca->unused)) |
| 186 | return; |
| 187 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 188 | if (!can_invalidate_bucket(ca, b)) |
| 189 | continue; |
| 190 | |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 191 | if (!GC_SECTORS_USED(b) && |
| 192 | bch_bucket_add_unused(ca, b)) |
| 193 | continue; |
| 194 | |
| 195 | if (!heap_full(&ca->heap)) |
| 196 | heap_add(&ca->heap, b, bucket_max_cmp); |
| 197 | else if (bucket_max_cmp(b, heap_peek(&ca->heap))) { |
| 198 | ca->heap.data[0] = b; |
| 199 | heap_sift(&ca->heap, 0, bucket_max_cmp); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 200 | } |
| 201 | } |
| 202 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 203 | for (i = ca->heap.used / 2 - 1; i >= 0; --i) |
| 204 | heap_sift(&ca->heap, i, bucket_min_cmp); |
| 205 | |
| 206 | while (!fifo_full(&ca->free_inc)) { |
| 207 | if (!heap_pop(&ca->heap, b, bucket_min_cmp)) { |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 208 | /* |
| 209 | * We don't want to be calling invalidate_buckets() |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 210 | * multiple times when it can't do anything |
| 211 | */ |
| 212 | ca->invalidate_needs_gc = 1; |
Kent Overstreet | 72a4451 | 2013-10-24 17:19:26 -0700 | [diff] [blame] | 213 | wake_up_gc(ca->set); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 214 | return; |
| 215 | } |
| 216 | |
| 217 | invalidate_one_bucket(ca, b); |
| 218 | } |
| 219 | } |
| 220 | |
| 221 | static void invalidate_buckets_fifo(struct cache *ca) |
| 222 | { |
| 223 | struct bucket *b; |
| 224 | size_t checked = 0; |
| 225 | |
| 226 | while (!fifo_full(&ca->free_inc)) { |
| 227 | if (ca->fifo_last_bucket < ca->sb.first_bucket || |
| 228 | ca->fifo_last_bucket >= ca->sb.nbuckets) |
| 229 | ca->fifo_last_bucket = ca->sb.first_bucket; |
| 230 | |
| 231 | b = ca->buckets + ca->fifo_last_bucket++; |
| 232 | |
| 233 | if (can_invalidate_bucket(ca, b)) |
| 234 | invalidate_one_bucket(ca, b); |
| 235 | |
| 236 | if (++checked >= ca->sb.nbuckets) { |
| 237 | ca->invalidate_needs_gc = 1; |
Kent Overstreet | 72a4451 | 2013-10-24 17:19:26 -0700 | [diff] [blame] | 238 | wake_up_gc(ca->set); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 239 | return; |
| 240 | } |
| 241 | } |
| 242 | } |
| 243 | |
| 244 | static void invalidate_buckets_random(struct cache *ca) |
| 245 | { |
| 246 | struct bucket *b; |
| 247 | size_t checked = 0; |
| 248 | |
| 249 | while (!fifo_full(&ca->free_inc)) { |
| 250 | size_t n; |
| 251 | get_random_bytes(&n, sizeof(n)); |
| 252 | |
| 253 | n %= (size_t) (ca->sb.nbuckets - ca->sb.first_bucket); |
| 254 | n += ca->sb.first_bucket; |
| 255 | |
| 256 | b = ca->buckets + n; |
| 257 | |
| 258 | if (can_invalidate_bucket(ca, b)) |
| 259 | invalidate_one_bucket(ca, b); |
| 260 | |
| 261 | if (++checked >= ca->sb.nbuckets / 2) { |
| 262 | ca->invalidate_needs_gc = 1; |
Kent Overstreet | 72a4451 | 2013-10-24 17:19:26 -0700 | [diff] [blame] | 263 | wake_up_gc(ca->set); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 264 | return; |
| 265 | } |
| 266 | } |
| 267 | } |
| 268 | |
| 269 | static void invalidate_buckets(struct cache *ca) |
| 270 | { |
| 271 | if (ca->invalidate_needs_gc) |
| 272 | return; |
| 273 | |
| 274 | switch (CACHE_REPLACEMENT(&ca->sb)) { |
| 275 | case CACHE_REPLACEMENT_LRU: |
| 276 | invalidate_buckets_lru(ca); |
| 277 | break; |
| 278 | case CACHE_REPLACEMENT_FIFO: |
| 279 | invalidate_buckets_fifo(ca); |
| 280 | break; |
| 281 | case CACHE_REPLACEMENT_RANDOM: |
| 282 | invalidate_buckets_random(ca); |
| 283 | break; |
| 284 | } |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 285 | |
Kent Overstreet | c37511b | 2013-04-26 15:39:55 -0700 | [diff] [blame] | 286 | trace_bcache_alloc_invalidate(ca); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 287 | } |
| 288 | |
| 289 | #define allocator_wait(ca, cond) \ |
| 290 | do { \ |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 291 | while (1) { \ |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 292 | set_current_state(TASK_INTERRUPTIBLE); \ |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 293 | if (cond) \ |
| 294 | break; \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 295 | \ |
| 296 | mutex_unlock(&(ca)->set->bucket_lock); \ |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 297 | if (kthread_should_stop()) \ |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 298 | return 0; \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 299 | \ |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 300 | try_to_freeze(); \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 301 | schedule(); \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 302 | mutex_lock(&(ca)->set->bucket_lock); \ |
| 303 | } \ |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 304 | __set_current_state(TASK_RUNNING); \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 305 | } while (0) |
| 306 | |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 307 | static int bch_allocator_thread(void *arg) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 308 | { |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 309 | struct cache *ca = arg; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 310 | |
| 311 | mutex_lock(&ca->set->bucket_lock); |
| 312 | |
| 313 | while (1) { |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 314 | /* |
| 315 | * First, we pull buckets off of the unused and free_inc lists, |
| 316 | * possibly issue discards to them, then we add the bucket to |
| 317 | * the free list: |
| 318 | */ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 319 | while (1) { |
| 320 | long bucket; |
| 321 | |
| 322 | if ((!atomic_read(&ca->set->prio_blocked) || |
| 323 | !CACHE_SYNC(&ca->set->sb)) && |
| 324 | !fifo_empty(&ca->unused)) |
| 325 | fifo_pop(&ca->unused, bucket); |
| 326 | else if (!fifo_empty(&ca->free_inc)) |
| 327 | fifo_pop(&ca->free_inc, bucket); |
| 328 | else |
| 329 | break; |
| 330 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 331 | if (ca->discard) { |
Kent Overstreet | 49b1212 | 2013-07-24 17:16:09 -0700 | [diff] [blame] | 332 | mutex_unlock(&ca->set->bucket_lock); |
| 333 | blkdev_issue_discard(ca->bdev, |
| 334 | bucket_to_sector(ca->set, bucket), |
| 335 | ca->sb.block_size, GFP_KERNEL, 0); |
| 336 | mutex_lock(&ca->set->bucket_lock); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 337 | } |
Kent Overstreet | 49b1212 | 2013-07-24 17:16:09 -0700 | [diff] [blame] | 338 | |
| 339 | allocator_wait(ca, !fifo_full(&ca->free)); |
| 340 | |
| 341 | fifo_push(&ca->free, bucket); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 342 | wake_up(&ca->set->bucket_wait); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 343 | } |
| 344 | |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 345 | /* |
| 346 | * We've run out of free buckets, we need to find some buckets |
| 347 | * we can invalidate. First, invalidate them in memory and add |
| 348 | * them to the free_inc list: |
| 349 | */ |
| 350 | |
| 351 | allocator_wait(ca, ca->set->gc_mark_valid && |
| 352 | (ca->need_save_prio > 64 || |
| 353 | !ca->invalidate_needs_gc)); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 354 | invalidate_buckets(ca); |
| 355 | |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 356 | /* |
| 357 | * Now, we write their new gens to disk so we can start writing |
| 358 | * new stuff to them: |
| 359 | */ |
| 360 | allocator_wait(ca, !atomic_read(&ca->set->prio_blocked)); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 361 | if (CACHE_SYNC(&ca->set->sb) && |
| 362 | (!fifo_empty(&ca->free_inc) || |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 363 | ca->need_save_prio > 64)) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 364 | bch_prio_write(ca); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 365 | } |
| 366 | } |
| 367 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 368 | long bch_bucket_alloc(struct cache *ca, unsigned watermark, bool wait) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 369 | { |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 370 | DEFINE_WAIT(w); |
| 371 | struct bucket *b; |
| 372 | long r; |
| 373 | |
| 374 | /* fastpath */ |
| 375 | if (fifo_used(&ca->free) > ca->watermark[watermark]) { |
| 376 | fifo_pop(&ca->free, r); |
| 377 | goto out; |
| 378 | } |
| 379 | |
| 380 | if (!wait) |
| 381 | return -1; |
| 382 | |
| 383 | while (1) { |
| 384 | if (fifo_used(&ca->free) > ca->watermark[watermark]) { |
| 385 | fifo_pop(&ca->free, r); |
| 386 | break; |
| 387 | } |
| 388 | |
| 389 | prepare_to_wait(&ca->set->bucket_wait, &w, |
| 390 | TASK_UNINTERRUPTIBLE); |
| 391 | |
| 392 | mutex_unlock(&ca->set->bucket_lock); |
| 393 | schedule(); |
| 394 | mutex_lock(&ca->set->bucket_lock); |
| 395 | } |
| 396 | |
| 397 | finish_wait(&ca->set->bucket_wait, &w); |
| 398 | out: |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 399 | wake_up_process(ca->alloc_thread); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 400 | |
Kent Overstreet | 280481d | 2013-10-24 16:36:03 -0700 | [diff] [blame] | 401 | if (expensive_debug_checks(ca->set)) { |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 402 | size_t iter; |
| 403 | long i; |
| 404 | |
| 405 | for (iter = 0; iter < prio_buckets(ca) * 2; iter++) |
| 406 | BUG_ON(ca->prio_buckets[iter] == (uint64_t) r); |
| 407 | |
| 408 | fifo_for_each(i, &ca->free, iter) |
| 409 | BUG_ON(i == r); |
| 410 | fifo_for_each(i, &ca->free_inc, iter) |
| 411 | BUG_ON(i == r); |
| 412 | fifo_for_each(i, &ca->unused, iter) |
| 413 | BUG_ON(i == r); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 414 | } |
Kent Overstreet | 280481d | 2013-10-24 16:36:03 -0700 | [diff] [blame] | 415 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 416 | b = ca->buckets + r; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 417 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 418 | BUG_ON(atomic_read(&b->pin) != 1); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 419 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 420 | SET_GC_SECTORS_USED(b, ca->sb.bucket_size); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 421 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 422 | if (watermark <= WATERMARK_METADATA) { |
| 423 | SET_GC_MARK(b, GC_MARK_METADATA); |
Nicholas Swenson | 981aa8c | 2013-11-07 17:53:19 -0800 | [diff] [blame^] | 424 | SET_GC_MOVE(b, 0); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 425 | b->prio = BTREE_PRIO; |
| 426 | } else { |
| 427 | SET_GC_MARK(b, GC_MARK_RECLAIMABLE); |
Nicholas Swenson | 981aa8c | 2013-11-07 17:53:19 -0800 | [diff] [blame^] | 428 | SET_GC_MOVE(b, 0); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 429 | b->prio = INITIAL_PRIO; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 430 | } |
| 431 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 432 | return r; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 433 | } |
| 434 | |
| 435 | void bch_bucket_free(struct cache_set *c, struct bkey *k) |
| 436 | { |
| 437 | unsigned i; |
| 438 | |
| 439 | for (i = 0; i < KEY_PTRS(k); i++) { |
| 440 | struct bucket *b = PTR_BUCKET(c, k, i); |
| 441 | |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 442 | SET_GC_MARK(b, GC_MARK_RECLAIMABLE); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 443 | SET_GC_SECTORS_USED(b, 0); |
| 444 | bch_bucket_add_unused(PTR_CACHE(c, k, i), b); |
| 445 | } |
| 446 | } |
| 447 | |
| 448 | int __bch_bucket_alloc_set(struct cache_set *c, unsigned watermark, |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 449 | struct bkey *k, int n, bool wait) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 450 | { |
| 451 | int i; |
| 452 | |
| 453 | lockdep_assert_held(&c->bucket_lock); |
| 454 | BUG_ON(!n || n > c->caches_loaded || n > 8); |
| 455 | |
| 456 | bkey_init(k); |
| 457 | |
| 458 | /* sort by free space/prio of oldest data in caches */ |
| 459 | |
| 460 | for (i = 0; i < n; i++) { |
| 461 | struct cache *ca = c->cache_by_alloc[i]; |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 462 | long b = bch_bucket_alloc(ca, watermark, wait); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 463 | |
| 464 | if (b == -1) |
| 465 | goto err; |
| 466 | |
| 467 | k->ptr[i] = PTR(ca->buckets[b].gen, |
| 468 | bucket_to_sector(c, b), |
| 469 | ca->sb.nr_this_dev); |
| 470 | |
| 471 | SET_KEY_PTRS(k, i + 1); |
| 472 | } |
| 473 | |
| 474 | return 0; |
| 475 | err: |
| 476 | bch_bucket_free(c, k); |
Kent Overstreet | 3a3b6a4 | 2013-07-24 16:46:42 -0700 | [diff] [blame] | 477 | bkey_put(c, k); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 478 | return -1; |
| 479 | } |
| 480 | |
| 481 | int bch_bucket_alloc_set(struct cache_set *c, unsigned watermark, |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 482 | struct bkey *k, int n, bool wait) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 483 | { |
| 484 | int ret; |
| 485 | mutex_lock(&c->bucket_lock); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 486 | ret = __bch_bucket_alloc_set(c, watermark, k, n, wait); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 487 | mutex_unlock(&c->bucket_lock); |
| 488 | return ret; |
| 489 | } |
| 490 | |
Kent Overstreet | 2599b53 | 2013-07-24 18:11:11 -0700 | [diff] [blame] | 491 | /* Sector allocator */ |
| 492 | |
| 493 | struct open_bucket { |
| 494 | struct list_head list; |
| 495 | unsigned last_write_point; |
| 496 | unsigned sectors_free; |
| 497 | BKEY_PADDED(key); |
| 498 | }; |
| 499 | |
| 500 | /* |
| 501 | * We keep multiple buckets open for writes, and try to segregate different |
| 502 | * write streams for better cache utilization: first we look for a bucket where |
| 503 | * the last write to it was sequential with the current write, and failing that |
| 504 | * we look for a bucket that was last used by the same task. |
| 505 | * |
| 506 | * The ideas is if you've got multiple tasks pulling data into the cache at the |
| 507 | * same time, you'll get better cache utilization if you try to segregate their |
| 508 | * data and preserve locality. |
| 509 | * |
| 510 | * For example, say you've starting Firefox at the same time you're copying a |
| 511 | * bunch of files. Firefox will likely end up being fairly hot and stay in the |
| 512 | * cache awhile, but the data you copied might not be; if you wrote all that |
| 513 | * data to the same buckets it'd get invalidated at the same time. |
| 514 | * |
| 515 | * Both of those tasks will be doing fairly random IO so we can't rely on |
| 516 | * detecting sequential IO to segregate their data, but going off of the task |
| 517 | * should be a sane heuristic. |
| 518 | */ |
| 519 | static struct open_bucket *pick_data_bucket(struct cache_set *c, |
| 520 | const struct bkey *search, |
| 521 | unsigned write_point, |
| 522 | struct bkey *alloc) |
| 523 | { |
| 524 | struct open_bucket *ret, *ret_task = NULL; |
| 525 | |
| 526 | list_for_each_entry_reverse(ret, &c->data_buckets, list) |
| 527 | if (!bkey_cmp(&ret->key, search)) |
| 528 | goto found; |
| 529 | else if (ret->last_write_point == write_point) |
| 530 | ret_task = ret; |
| 531 | |
| 532 | ret = ret_task ?: list_first_entry(&c->data_buckets, |
| 533 | struct open_bucket, list); |
| 534 | found: |
| 535 | if (!ret->sectors_free && KEY_PTRS(alloc)) { |
| 536 | ret->sectors_free = c->sb.bucket_size; |
| 537 | bkey_copy(&ret->key, alloc); |
| 538 | bkey_init(alloc); |
| 539 | } |
| 540 | |
| 541 | if (!ret->sectors_free) |
| 542 | ret = NULL; |
| 543 | |
| 544 | return ret; |
| 545 | } |
| 546 | |
| 547 | /* |
| 548 | * Allocates some space in the cache to write to, and k to point to the newly |
| 549 | * allocated space, and updates KEY_SIZE(k) and KEY_OFFSET(k) (to point to the |
| 550 | * end of the newly allocated space). |
| 551 | * |
| 552 | * May allocate fewer sectors than @sectors, KEY_SIZE(k) indicates how many |
| 553 | * sectors were actually allocated. |
| 554 | * |
| 555 | * If s->writeback is true, will not fail. |
| 556 | */ |
| 557 | bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, unsigned sectors, |
| 558 | unsigned write_point, unsigned write_prio, bool wait) |
| 559 | { |
| 560 | struct open_bucket *b; |
| 561 | BKEY_PADDED(key) alloc; |
| 562 | unsigned i; |
| 563 | |
| 564 | /* |
| 565 | * We might have to allocate a new bucket, which we can't do with a |
| 566 | * spinlock held. So if we have to allocate, we drop the lock, allocate |
| 567 | * and then retry. KEY_PTRS() indicates whether alloc points to |
| 568 | * allocated bucket(s). |
| 569 | */ |
| 570 | |
| 571 | bkey_init(&alloc.key); |
| 572 | spin_lock(&c->data_bucket_lock); |
| 573 | |
| 574 | while (!(b = pick_data_bucket(c, k, write_point, &alloc.key))) { |
| 575 | unsigned watermark = write_prio |
| 576 | ? WATERMARK_MOVINGGC |
| 577 | : WATERMARK_NONE; |
| 578 | |
| 579 | spin_unlock(&c->data_bucket_lock); |
| 580 | |
| 581 | if (bch_bucket_alloc_set(c, watermark, &alloc.key, 1, wait)) |
| 582 | return false; |
| 583 | |
| 584 | spin_lock(&c->data_bucket_lock); |
| 585 | } |
| 586 | |
| 587 | /* |
| 588 | * If we had to allocate, we might race and not need to allocate the |
| 589 | * second time we call find_data_bucket(). If we allocated a bucket but |
| 590 | * didn't use it, drop the refcount bch_bucket_alloc_set() took: |
| 591 | */ |
| 592 | if (KEY_PTRS(&alloc.key)) |
Kent Overstreet | 3a3b6a4 | 2013-07-24 16:46:42 -0700 | [diff] [blame] | 593 | bkey_put(c, &alloc.key); |
Kent Overstreet | 2599b53 | 2013-07-24 18:11:11 -0700 | [diff] [blame] | 594 | |
| 595 | for (i = 0; i < KEY_PTRS(&b->key); i++) |
| 596 | EBUG_ON(ptr_stale(c, &b->key, i)); |
| 597 | |
| 598 | /* Set up the pointer to the space we're allocating: */ |
| 599 | |
| 600 | for (i = 0; i < KEY_PTRS(&b->key); i++) |
| 601 | k->ptr[i] = b->key.ptr[i]; |
| 602 | |
| 603 | sectors = min(sectors, b->sectors_free); |
| 604 | |
| 605 | SET_KEY_OFFSET(k, KEY_OFFSET(k) + sectors); |
| 606 | SET_KEY_SIZE(k, sectors); |
| 607 | SET_KEY_PTRS(k, KEY_PTRS(&b->key)); |
| 608 | |
| 609 | /* |
| 610 | * Move b to the end of the lru, and keep track of what this bucket was |
| 611 | * last used for: |
| 612 | */ |
| 613 | list_move_tail(&b->list, &c->data_buckets); |
| 614 | bkey_copy_key(&b->key, k); |
| 615 | b->last_write_point = write_point; |
| 616 | |
| 617 | b->sectors_free -= sectors; |
| 618 | |
| 619 | for (i = 0; i < KEY_PTRS(&b->key); i++) { |
| 620 | SET_PTR_OFFSET(&b->key, i, PTR_OFFSET(&b->key, i) + sectors); |
| 621 | |
| 622 | atomic_long_add(sectors, |
| 623 | &PTR_CACHE(c, &b->key, i)->sectors_written); |
| 624 | } |
| 625 | |
| 626 | if (b->sectors_free < c->sb.block_size) |
| 627 | b->sectors_free = 0; |
| 628 | |
| 629 | /* |
| 630 | * k takes refcounts on the buckets it points to until it's inserted |
| 631 | * into the btree, but if we're done with this bucket we just transfer |
| 632 | * get_data_bucket()'s refcount. |
| 633 | */ |
| 634 | if (b->sectors_free) |
| 635 | for (i = 0; i < KEY_PTRS(&b->key); i++) |
| 636 | atomic_inc(&PTR_BUCKET(c, &b->key, i)->pin); |
| 637 | |
| 638 | spin_unlock(&c->data_bucket_lock); |
| 639 | return true; |
| 640 | } |
| 641 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 642 | /* Init */ |
| 643 | |
Kent Overstreet | 2599b53 | 2013-07-24 18:11:11 -0700 | [diff] [blame] | 644 | void bch_open_buckets_free(struct cache_set *c) |
| 645 | { |
| 646 | struct open_bucket *b; |
| 647 | |
| 648 | while (!list_empty(&c->data_buckets)) { |
| 649 | b = list_first_entry(&c->data_buckets, |
| 650 | struct open_bucket, list); |
| 651 | list_del(&b->list); |
| 652 | kfree(b); |
| 653 | } |
| 654 | } |
| 655 | |
| 656 | int bch_open_buckets_alloc(struct cache_set *c) |
| 657 | { |
| 658 | int i; |
| 659 | |
| 660 | spin_lock_init(&c->data_bucket_lock); |
| 661 | |
| 662 | for (i = 0; i < 6; i++) { |
| 663 | struct open_bucket *b = kzalloc(sizeof(*b), GFP_KERNEL); |
| 664 | if (!b) |
| 665 | return -ENOMEM; |
| 666 | |
| 667 | list_add(&b->list, &c->data_buckets); |
| 668 | } |
| 669 | |
| 670 | return 0; |
| 671 | } |
| 672 | |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 673 | int bch_cache_allocator_start(struct cache *ca) |
| 674 | { |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 675 | struct task_struct *k = kthread_run(bch_allocator_thread, |
| 676 | ca, "bcache_allocator"); |
| 677 | if (IS_ERR(k)) |
| 678 | return PTR_ERR(k); |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 679 | |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 680 | ca->alloc_thread = k; |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 681 | return 0; |
| 682 | } |
| 683 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 684 | int bch_cache_allocator_init(struct cache *ca) |
| 685 | { |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 686 | /* |
| 687 | * Reserve: |
| 688 | * Prio/gen writes first |
| 689 | * Then 8 for btree allocations |
| 690 | * Then half for the moving garbage collector |
| 691 | */ |
| 692 | |
| 693 | ca->watermark[WATERMARK_PRIO] = 0; |
| 694 | |
| 695 | ca->watermark[WATERMARK_METADATA] = prio_buckets(ca); |
| 696 | |
| 697 | ca->watermark[WATERMARK_MOVINGGC] = 8 + |
| 698 | ca->watermark[WATERMARK_METADATA]; |
| 699 | |
| 700 | ca->watermark[WATERMARK_NONE] = ca->free.size / 2 + |
| 701 | ca->watermark[WATERMARK_MOVINGGC]; |
| 702 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 703 | return 0; |
| 704 | } |