1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 /* 27 * Copyright (c) 2011, 2019 by Delphix. All rights reserved. 28 */ 29 30 #ifndef _SYS_METASLAB_IMPL_H 31 #define _SYS_METASLAB_IMPL_H 32 33 #include <sys/metaslab.h> 34 #include <sys/space_map.h> 35 #include <sys/range_tree.h> 36 #include <sys/vdev.h> 37 #include <sys/txg.h> 38 #include <sys/avl.h> 39 #include <sys/multilist.h> 40 41 #ifdef __cplusplus 42 extern "C" { 43 #endif 44 45 /* 46 * Metaslab allocation tracing record. 47 */ 48 typedef struct metaslab_alloc_trace { 49 list_node_t mat_list_node; 50 metaslab_group_t *mat_mg; 51 metaslab_t *mat_msp; 52 uint64_t mat_size; 53 uint64_t mat_weight; 54 uint32_t mat_dva_id; 55 uint64_t mat_offset; 56 int mat_allocator; 57 } metaslab_alloc_trace_t; 58 59 /* 60 * Used by the metaslab allocation tracing facility to indicate 61 * error conditions. These errors are stored to the offset member 62 * of the metaslab_alloc_trace_t record and displayed by mdb. 63 */ 64 typedef enum trace_alloc_type { 65 TRACE_ALLOC_FAILURE = -1ULL, 66 TRACE_TOO_SMALL = -2ULL, 67 TRACE_FORCE_GANG = -3ULL, 68 TRACE_NOT_ALLOCATABLE = -4ULL, 69 TRACE_GROUP_FAILURE = -5ULL, 70 TRACE_ENOSPC = -6ULL, 71 TRACE_CONDENSING = -7ULL, 72 TRACE_VDEV_ERROR = -8ULL, 73 TRACE_DISABLED = -9ULL, 74 } trace_alloc_type_t; 75 76 #define METASLAB_WEIGHT_PRIMARY (1ULL << 63) 77 #define METASLAB_WEIGHT_SECONDARY (1ULL << 62) 78 #define METASLAB_WEIGHT_CLAIM (1ULL << 61) 79 #define METASLAB_WEIGHT_TYPE (1ULL << 60) 80 #define METASLAB_ACTIVE_MASK \ 81 (METASLAB_WEIGHT_PRIMARY | METASLAB_WEIGHT_SECONDARY | \ 82 METASLAB_WEIGHT_CLAIM) 83 84 /* 85 * The metaslab weight is used to encode the amount of free space in a 86 * metaslab, such that the "best" metaslab appears first when sorting the 87 * metaslabs by weight. The weight (and therefore the "best" metaslab) can 88 * be determined in two different ways: by computing a weighted sum of all 89 * the free space in the metaslab (a space based weight) or by counting only 90 * the free segments of the largest size (a segment based weight). We prefer 91 * the segment based weight because it reflects how the free space is 92 * comprised, but we cannot always use it -- legacy pools do not have the 93 * space map histogram information necessary to determine the largest 94 * contiguous regions. Pools that have the space map histogram determine 95 * the segment weight by looking at each bucket in the histogram and 96 * determining the free space whose size in bytes is in the range: 97 * [2^i, 2^(i+1)) 98 * We then encode the largest index, i, that contains regions into the 99 * segment-weighted value. 100 * 101 * Space-based weight: 102 * 103 * 64 56 48 40 32 24 16 8 0 104 * +-------+-------+-------+-------+-------+-------+-------+-------+ 105 * |PSC1| weighted-free space | 106 * +-------+-------+-------+-------+-------+-------+-------+-------+ 107 * 108 * PS - indicates primary and secondary activation 109 * C - indicates activation for claimed block zio 110 * space - the fragmentation-weighted space 111 * 112 * Segment-based weight: 113 * 114 * 64 56 48 40 32 24 16 8 0 115 * +-------+-------+-------+-------+-------+-------+-------+-------+ 116 * |PSC0| idx| count of segments in region | 117 * +-------+-------+-------+-------+-------+-------+-------+-------+ 118 * 119 * PS - indicates primary and secondary activation 120 * C - indicates activation for claimed block zio 121 * idx - index for the highest bucket in the histogram 122 * count - number of segments in the specified bucket 123 */ 124 #define WEIGHT_GET_ACTIVE(weight) BF64_GET((weight), 61, 3) 125 #define WEIGHT_SET_ACTIVE(weight, x) BF64_SET((weight), 61, 3, x) 126 127 #define WEIGHT_IS_SPACEBASED(weight) \ 128 ((weight) == 0 || BF64_GET((weight), 60, 1)) 129 #define WEIGHT_SET_SPACEBASED(weight) BF64_SET((weight), 60, 1, 1) 130 131 /* 132 * These macros are only applicable to segment-based weighting. 133 */ 134 #define WEIGHT_GET_INDEX(weight) BF64_GET((weight), 54, 6) 135 #define WEIGHT_SET_INDEX(weight, x) BF64_SET((weight), 54, 6, x) 136 #define WEIGHT_GET_COUNT(weight) BF64_GET((weight), 0, 54) 137 #define WEIGHT_SET_COUNT(weight, x) BF64_SET((weight), 0, 54, x) 138 139 /* 140 * A metaslab class encompasses a category of allocatable top-level vdevs. 141 * Each top-level vdev is associated with a metaslab group which defines 142 * the allocatable region for that vdev. Examples of these categories include 143 * "normal" for data block allocations (i.e. main pool allocations) or "log" 144 * for allocations designated for intent log devices (i.e. slog devices). 145 * When a block allocation is requested from the SPA it is associated with a 146 * metaslab_class_t, and only top-level vdevs (i.e. metaslab groups) belonging 147 * to the class can be used to satisfy that request. Allocations are done 148 * by traversing the metaslab groups that are linked off of the mc_rotor field. 149 * This rotor points to the next metaslab group where allocations will be 150 * attempted. Allocating a block is a 3 step process -- select the metaslab 151 * group, select the metaslab, and then allocate the block. The metaslab 152 * class defines the low-level block allocator that will be used as the 153 * final step in allocation. These allocators are pluggable allowing each class 154 * to use a block allocator that best suits that class. 155 */ 156 struct metaslab_class { 157 kmutex_t mc_lock; 158 spa_t *mc_spa; 159 metaslab_group_t *mc_rotor; 160 metaslab_ops_t *mc_ops; 161 uint64_t mc_aliquot; 162 163 /* 164 * Track the number of metaslab groups that have been initialized 165 * and can accept allocations. An initialized metaslab group is 166 * one has been completely added to the config (i.e. we have 167 * updated the MOS config and the space has been added to the pool). 168 */ 169 uint64_t mc_groups; 170 171 /* 172 * Toggle to enable/disable the allocation throttle. 173 */ 174 boolean_t mc_alloc_throttle_enabled; 175 176 /* 177 * The allocation throttle works on a reservation system. Whenever 178 * an asynchronous zio wants to perform an allocation it must 179 * first reserve the number of blocks that it wants to allocate. 180 * If there aren't sufficient slots available for the pending zio 181 * then that I/O is throttled until more slots free up. The current 182 * number of reserved allocations is maintained by the mc_alloc_slots 183 * refcount. The mc_alloc_max_slots value determines the maximum 184 * number of allocations that the system allows. Gang blocks are 185 * allowed to reserve slots even if we've reached the maximum 186 * number of allocations allowed. 187 */ 188 uint64_t *mc_alloc_max_slots; 189 zfs_refcount_t *mc_alloc_slots; 190 191 uint64_t mc_alloc_groups; /* # of allocatable groups */ 192 193 uint64_t mc_alloc; /* total allocated space */ 194 uint64_t mc_deferred; /* total deferred frees */ 195 uint64_t mc_space; /* total space (alloc + free) */ 196 uint64_t mc_dspace; /* total deflated space */ 197 uint64_t mc_histogram[RANGE_TREE_HISTOGRAM_SIZE]; 198 199 /* 200 * List of all loaded metaslabs in the class, sorted in order of most 201 * recent use. 202 */ 203 multilist_t *mc_metaslab_txg_list; 204 }; 205 206 /* 207 * Metaslab groups encapsulate all the allocatable regions (i.e. metaslabs) 208 * of a top-level vdev. They are linked togther to form a circular linked 209 * list and can belong to only one metaslab class. Metaslab groups may become 210 * ineligible for allocations for a number of reasons such as limited free 211 * space, fragmentation, or going offline. When this happens the allocator will 212 * simply find the next metaslab group in the linked list and attempt 213 * to allocate from that group instead. 214 */ 215 struct metaslab_group { 216 kmutex_t mg_lock; 217 metaslab_t **mg_primaries; 218 metaslab_t **mg_secondaries; 219 avl_tree_t mg_metaslab_tree; 220 uint64_t mg_aliquot; 221 boolean_t mg_allocatable; /* can we allocate? */ 222 uint64_t mg_ms_ready; 223 224 /* 225 * A metaslab group is considered to be initialized only after 226 * we have updated the MOS config and added the space to the pool. 227 * We only allow allocation attempts to a metaslab group if it 228 * has been initialized. 229 */ 230 boolean_t mg_initialized; 231 232 uint64_t mg_free_capacity; /* percentage free */ 233 int64_t mg_bias; 234 int64_t mg_activation_count; 235 metaslab_class_t *mg_class; 236 vdev_t *mg_vd; 237 taskq_t *mg_taskq; 238 metaslab_group_t *mg_prev; 239 metaslab_group_t *mg_next; 240 241 /* 242 * In order for the allocation throttle to function properly, we cannot 243 * have too many IOs going to each disk by default; the throttle 244 * operates by allocating more work to disks that finish quickly, so 245 * allocating larger chunks to each disk reduces its effectiveness. 246 * However, if the number of IOs going to each allocator is too small, 247 * we will not perform proper aggregation at the vdev_queue layer, 248 * also resulting in decreased performance. Therefore, we will use a 249 * ramp-up strategy. 250 * 251 * Each allocator in each metaslab group has a current queue depth 252 * (mg_alloc_queue_depth[allocator]) and a current max queue depth 253 * (mg_cur_max_alloc_queue_depth[allocator]), and each metaslab group 254 * has an absolute max queue depth (mg_max_alloc_queue_depth). We 255 * add IOs to an allocator until the mg_alloc_queue_depth for that 256 * allocator hits the cur_max. Every time an IO completes for a given 257 * allocator on a given metaslab group, we increment its cur_max until 258 * it reaches mg_max_alloc_queue_depth. The cur_max resets every txg to 259 * help protect against disks that decrease in performance over time. 260 * 261 * It's possible for an allocator to handle more allocations than 262 * its max. This can occur when gang blocks are required or when other 263 * groups are unable to handle their share of allocations. 264 */ 265 uint64_t mg_max_alloc_queue_depth; 266 uint64_t *mg_cur_max_alloc_queue_depth; 267 zfs_refcount_t *mg_alloc_queue_depth; 268 int mg_allocators; 269 /* 270 * A metalab group that can no longer allocate the minimum block 271 * size will set mg_no_free_space. Once a metaslab group is out 272 * of space then its share of work must be distributed to other 273 * groups. 274 */ 275 boolean_t mg_no_free_space; 276 277 uint64_t mg_allocations; 278 uint64_t mg_failed_allocations; 279 uint64_t mg_fragmentation; 280 uint64_t mg_histogram[RANGE_TREE_HISTOGRAM_SIZE]; 281 282 int mg_ms_disabled; 283 boolean_t mg_disabled_updating; 284 kmutex_t mg_ms_disabled_lock; 285 kcondvar_t mg_ms_disabled_cv; 286 }; 287 288 /* 289 * This value defines the number of elements in the ms_lbas array. The value 290 * of 64 was chosen as it covers all power of 2 buckets up to UINT64_MAX. 291 * This is the equivalent of highbit(UINT64_MAX). 292 */ 293 #define MAX_LBAS 64 294 295 /* 296 * Each metaslab maintains a set of in-core trees to track metaslab 297 * operations. The in-core free tree (ms_allocatable) contains the list of 298 * free segments which are eligible for allocation. As blocks are 299 * allocated, the allocated segment are removed from the ms_allocatable and 300 * added to a per txg allocation tree (ms_allocating). As blocks are 301 * freed, they are added to the free tree (ms_freeing). These trees 302 * allow us to process all allocations and frees in syncing context 303 * where it is safe to update the on-disk space maps. An additional set 304 * of in-core trees is maintained to track deferred frees 305 * (ms_defer). Once a block is freed it will move from the 306 * ms_freed to the ms_defer tree. A deferred free means that a block 307 * has been freed but cannot be used by the pool until TXG_DEFER_SIZE 308 * transactions groups later. For example, a block that is freed in txg 309 * 50 will not be available for reallocation until txg 52 (50 + 310 * TXG_DEFER_SIZE). This provides a safety net for uberblock rollback. 311 * A pool could be safely rolled back TXG_DEFERS_SIZE transactions 312 * groups and ensure that no block has been reallocated. 313 * 314 * The simplified transition diagram looks like this: 315 * 316 * 317 * ALLOCATE 318 * | 319 * V 320 * free segment (ms_allocatable) -> ms_allocating[4] -> (write to space map) 321 * ^ 322 * | ms_freeing <--- FREE 323 * | | 324 * | v 325 * | ms_freed 326 * | | 327 * +-------- ms_defer[2] <-------+-------> (write to space map) 328 * 329 * 330 * Each metaslab's space is tracked in a single space map in the MOS, 331 * which is only updated in syncing context. Each time we sync a txg, 332 * we append the allocs and frees from that txg to the space map. The 333 * pool space is only updated once all metaslabs have finished syncing. 334 * 335 * To load the in-core free tree we read the space map from disk. This 336 * object contains a series of alloc and free records that are combined 337 * to make up the list of all free segments in this metaslab. These 338 * segments are represented in-core by the ms_allocatable and are stored 339 * in an AVL tree. 340 * 341 * As the space map grows (as a result of the appends) it will 342 * eventually become space-inefficient. When the metaslab's in-core 343 * free tree is zfs_condense_pct/100 times the size of the minimal 344 * on-disk representation, we rewrite it in its minimized form. If a 345 * metaslab needs to condense then we must set the ms_condensing flag to 346 * ensure that allocations are not performed on the metaslab that is 347 * being written. 348 */ 349 struct metaslab { 350 /* 351 * This is the main lock of the metaslab and its purpose is to 352 * coordinate our allocations and frees [e.g metaslab_block_alloc(), 353 * metaslab_free_concrete(), ..etc] with our various syncing 354 * procedures [e.g. metaslab_sync(), metaslab_sync_done(), ..etc]. 355 * 356 * The lock is also used during some miscellaneous operations like 357 * using the metaslab's histogram for the metaslab group's histogram 358 * aggregation, or marking the metaslab for initialization. 359 */ 360 kmutex_t ms_lock; 361 362 /* 363 * Acquired together with the ms_lock whenever we expect to 364 * write to metaslab data on-disk (i.e flushing entries to 365 * the metaslab's space map). It helps coordinate readers of 366 * the metaslab's space map [see spa_vdev_remove_thread()] 367 * with writers [see metaslab_sync() or metaslab_flush()]. 368 * 369 * Note that metaslab_load(), even though a reader, uses 370 * a completely different mechanism to deal with the reading 371 * of the metaslab's space map based on ms_synced_length. That 372 * said, the function still uses the ms_sync_lock after it 373 * has read the ms_sm [see relevant comment in metaslab_load() 374 * as to why]. 375 */ 376 kmutex_t ms_sync_lock; 377 378 kcondvar_t ms_load_cv; 379 space_map_t *ms_sm; 380 uint64_t ms_id; 381 uint64_t ms_start; 382 uint64_t ms_size; 383 uint64_t ms_fragmentation; 384 385 range_tree_t *ms_allocating[TXG_SIZE]; 386 range_tree_t *ms_allocatable; 387 uint64_t ms_allocated_this_txg; 388 uint64_t ms_allocating_total; 389 390 /* 391 * The following range trees are accessed only from syncing context. 392 * ms_free*tree only have entries while syncing, and are empty 393 * between syncs. 394 */ 395 range_tree_t *ms_freeing; /* to free this syncing txg */ 396 range_tree_t *ms_freed; /* already freed this syncing txg */ 397 range_tree_t *ms_defer[TXG_DEFER_SIZE]; 398 range_tree_t *ms_checkpointing; /* to add to the checkpoint */ 399 400 /* 401 * The ms_trim tree is the set of allocatable segments which are 402 * eligible for trimming. (When the metaslab is loaded, it's a 403 * subset of ms_allocatable.) It's kept in-core as long as the 404 * autotrim property is set and is not vacated when the metaslab 405 * is unloaded. Its purpose is to aggregate freed ranges to 406 * facilitate efficient trimming. 407 */ 408 range_tree_t *ms_trim; 409 410 boolean_t ms_condensing; /* condensing? */ 411 boolean_t ms_condense_wanted; 412 413 /* 414 * The number of consumers which have disabled the metaslab. 415 */ 416 uint64_t ms_disabled; 417 418 /* 419 * We must always hold the ms_lock when modifying ms_loaded 420 * and ms_loading. 421 */ 422 boolean_t ms_loaded; 423 boolean_t ms_loading; 424 kcondvar_t ms_flush_cv; 425 boolean_t ms_flushing; 426 427 /* 428 * The following histograms count entries that are in the 429 * metaslab's space map (and its histogram) but are not in 430 * ms_allocatable yet, because they are in ms_freed, ms_freeing, 431 * or ms_defer[]. 432 * 433 * When the metaslab is not loaded, its ms_weight needs to 434 * reflect what is allocatable (i.e. what will be part of 435 * ms_allocatable if it is loaded). The weight is computed from 436 * the spacemap histogram, but that includes ranges that are 437 * not yet allocatable (because they are in ms_freed, 438 * ms_freeing, or ms_defer[]). Therefore, when calculating the 439 * weight, we need to remove those ranges. 440 * 441 * The ranges in the ms_freed and ms_defer[] range trees are all 442 * present in the spacemap. However, the spacemap may have 443 * multiple entries to represent a contiguous range, because it 444 * is written across multiple sync passes, but the changes of 445 * all sync passes are consolidated into the range trees. 446 * Adjacent ranges that are freed in different sync passes of 447 * one txg will be represented separately (as 2 or more entries) 448 * in the space map (and its histogram), but these adjacent 449 * ranges will be consolidated (represented as one entry) in the 450 * ms_freed/ms_defer[] range trees (and their histograms). 451 * 452 * When calculating the weight, we can not simply subtract the 453 * range trees' histograms from the spacemap's histogram, 454 * because the range trees' histograms may have entries in 455 * higher buckets than the spacemap, due to consolidation. 456 * Instead we must subtract the exact entries that were added to 457 * the spacemap's histogram. ms_synchist and ms_deferhist[] 458 * represent these exact entries, so we can subtract them from 459 * the spacemap's histogram when calculating ms_weight. 460 * 461 * ms_synchist represents the same ranges as ms_freeing + 462 * ms_freed, but without consolidation across sync passes. 463 * 464 * ms_deferhist[i] represents the same ranges as ms_defer[i], 465 * but without consolidation across sync passes. 466 */ 467 uint64_t ms_synchist[SPACE_MAP_HISTOGRAM_SIZE]; 468 uint64_t ms_deferhist[TXG_DEFER_SIZE][SPACE_MAP_HISTOGRAM_SIZE]; 469 470 /* 471 * Tracks the exact amount of allocated space of this metaslab 472 * (and specifically the metaslab's space map) up to the most 473 * recently completed sync pass [see usage in metaslab_sync()]. 474 */ 475 uint64_t ms_allocated_space; 476 int64_t ms_deferspace; /* sum of ms_defermap[] space */ 477 uint64_t ms_weight; /* weight vs. others in group */ 478 uint64_t ms_activation_weight; /* activation weight */ 479 480 /* 481 * Track of whenever a metaslab is selected for loading or allocation. 482 * We use this value to determine how long the metaslab should 483 * stay cached. 484 */ 485 uint64_t ms_selected_txg; 486 /* 487 * ms_load/unload_time can be used for performance monitoring 488 * (e.g. by dtrace or mdb). 489 */ 490 hrtime_t ms_load_time; /* time last loaded */ 491 hrtime_t ms_unload_time; /* time last unloaded */ 492 hrtime_t ms_selected_time; /* time last allocated from */ 493 494 uint64_t ms_alloc_txg; /* last successful alloc (debug only) */ 495 uint64_t ms_max_size; /* maximum allocatable size */ 496 497 /* 498 * -1 if it's not active in an allocator, otherwise set to the allocator 499 * this metaslab is active for. 500 */ 501 int ms_allocator; 502 boolean_t ms_primary; /* Only valid if ms_allocator is not -1 */ 503 504 /* 505 * The metaslab block allocators can optionally use a size-ordered 506 * range tree and/or an array of LBAs. Not all allocators use 507 * this functionality. The ms_allocatable_by_size should always 508 * contain the same number of segments as the ms_allocatable. The 509 * only difference is that the ms_allocatable_by_size is ordered by 510 * segment sizes. 511 */ 512 zfs_btree_t ms_allocatable_by_size; 513 zfs_btree_t ms_unflushed_frees_by_size; 514 uint64_t ms_lbas[MAX_LBAS]; 515 516 metaslab_group_t *ms_group; /* metaslab group */ 517 avl_node_t ms_group_node; /* node in metaslab group tree */ 518 txg_node_t ms_txg_node; /* per-txg dirty metaslab links */ 519 avl_node_t ms_spa_txg_node; /* node in spa_metaslabs_by_txg */ 520 /* 521 * Node in metaslab class's selected txg list 522 */ 523 multilist_node_t ms_class_txg_node; 524 525 /* 526 * Allocs and frees that are committed to the vdev log spacemap but 527 * not yet to this metaslab's spacemap. 528 */ 529 range_tree_t *ms_unflushed_allocs; 530 range_tree_t *ms_unflushed_frees; 531 532 /* 533 * We have flushed entries up to but not including this TXG. In 534 * other words, all changes from this TXG and onward should not 535 * be in this metaslab's space map and must be read from the 536 * log space maps. 537 */ 538 uint64_t ms_unflushed_txg; 539 540 /* updated every time we are done syncing the metaslab's space map */ 541 uint64_t ms_synced_length; 542 543 boolean_t ms_new; 544 }; 545 546 typedef struct metaslab_unflushed_phys { 547 /* on-disk counterpart of ms_unflushed_txg */ 548 uint64_t msp_unflushed_txg; 549 } metaslab_unflushed_phys_t; 550 551 #ifdef __cplusplus 552 } 553 #endif 554 555 #endif /* _SYS_METASLAB_IMPL_H */ 556