/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright 2009 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ /* * Copyright (c) 2011, 2019 by Delphix. All rights reserved. */ #ifndef _SYS_METASLAB_IMPL_H #define _SYS_METASLAB_IMPL_H #include <sys/metaslab.h> #include <sys/space_map.h> #include <sys/range_tree.h> #include <sys/vdev.h> #include <sys/txg.h> #include <sys/avl.h> #include <sys/multilist.h> #ifdef __cplusplus extern "C" { #endif /* * Metaslab allocation tracing record. */ typedef struct metaslab_alloc_trace { list_node_t mat_list_node; metaslab_group_t *mat_mg; metaslab_t *mat_msp; uint64_t mat_size; uint64_t mat_weight; uint32_t mat_dva_id; uint64_t mat_offset; int mat_allocator; } metaslab_alloc_trace_t; /* * Used by the metaslab allocation tracing facility to indicate * error conditions. These errors are stored to the offset member * of the metaslab_alloc_trace_t record and displayed by mdb. */ typedef enum trace_alloc_type { TRACE_ALLOC_FAILURE = -1ULL, TRACE_TOO_SMALL = -2ULL, TRACE_FORCE_GANG = -3ULL, TRACE_NOT_ALLOCATABLE = -4ULL, TRACE_GROUP_FAILURE = -5ULL, TRACE_ENOSPC = -6ULL, TRACE_CONDENSING = -7ULL, TRACE_VDEV_ERROR = -8ULL, TRACE_DISABLED = -9ULL, } trace_alloc_type_t; #define METASLAB_WEIGHT_PRIMARY (1ULL << 63) #define METASLAB_WEIGHT_SECONDARY (1ULL << 62) #define METASLAB_WEIGHT_CLAIM (1ULL << 61) #define METASLAB_WEIGHT_TYPE (1ULL << 60) #define METASLAB_ACTIVE_MASK \ (METASLAB_WEIGHT_PRIMARY | METASLAB_WEIGHT_SECONDARY | \ METASLAB_WEIGHT_CLAIM) /* * The metaslab weight is used to encode the amount of free space in a * metaslab, such that the "best" metaslab appears first when sorting the * metaslabs by weight. The weight (and therefore the "best" metaslab) can * be determined in two different ways: by computing a weighted sum of all * the free space in the metaslab (a space based weight) or by counting only * the free segments of the largest size (a segment based weight). We prefer * the segment based weight because it reflects how the free space is * comprised, but we cannot always use it -- legacy pools do not have the * space map histogram information necessary to determine the largest * contiguous regions. Pools that have the space map histogram determine * the segment weight by looking at each bucket in the histogram and * determining the free space whose size in bytes is in the range: * [2^i, 2^(i+1)) * We then encode the largest index, i, that contains regions into the * segment-weighted value. * * Space-based weight: * * 64 56 48 40 32 24 16 8 0 * +-------+-------+-------+-------+-------+-------+-------+-------+ * |PSC1| weighted-free space | * +-------+-------+-------+-------+-------+-------+-------+-------+ * * PS - indicates primary and secondary activation * C - indicates activation for claimed block zio * space - the fragmentation-weighted space * * Segment-based weight: * * 64 56 48 40 32 24 16 8 0 * +-------+-------+-------+-------+-------+-------+-------+-------+ * |PSC0| idx| count of segments in region | * +-------+-------+-------+-------+-------+-------+-------+-------+ * * PS - indicates primary and secondary activation * C - indicates activation for claimed block zio * idx - index for the highest bucket in the histogram * count - number of segments in the specified bucket */ #define WEIGHT_GET_ACTIVE(weight) BF64_GET((weight), 61, 3) #define WEIGHT_SET_ACTIVE(weight, x) BF64_SET((weight), 61, 3, x) #define WEIGHT_IS_SPACEBASED(weight) \ ((weight) == 0 || BF64_GET((weight), 60, 1)) #define WEIGHT_SET_SPACEBASED(weight) BF64_SET((weight), 60, 1, 1) /* * These macros are only applicable to segment-based weighting. */ #define WEIGHT_GET_INDEX(weight) BF64_GET((weight), 54, 6) #define WEIGHT_SET_INDEX(weight, x) BF64_SET((weight), 54, 6, x) #define WEIGHT_GET_COUNT(weight) BF64_GET((weight), 0, 54) #define WEIGHT_SET_COUNT(weight, x) BF64_SET((weight), 0, 54, x) /* * A metaslab class encompasses a category of allocatable top-level vdevs. * Each top-level vdev is associated with a metaslab group which defines * the allocatable region for that vdev. Examples of these categories include * "normal" for data block allocations (i.e. main pool allocations) or "log" * for allocations designated for intent log devices (i.e. slog devices). * When a block allocation is requested from the SPA it is associated with a * metaslab_class_t, and only top-level vdevs (i.e. metaslab groups) belonging * to the class can be used to satisfy that request. Allocations are done * by traversing the metaslab groups that are linked off of the mc_rotor field. * This rotor points to the next metaslab group where allocations will be * attempted. Allocating a block is a 3 step process -- select the metaslab * group, select the metaslab, and then allocate the block. The metaslab * class defines the low-level block allocator that will be used as the * final step in allocation. These allocators are pluggable allowing each class * to use a block allocator that best suits that class. */ struct metaslab_class { kmutex_t mc_lock; spa_t *mc_spa; metaslab_group_t *mc_rotor; metaslab_ops_t *mc_ops; uint64_t mc_aliquot; /* * Track the number of metaslab groups that have been initialized * and can accept allocations. An initialized metaslab group is * one has been completely added to the config (i.e. we have * updated the MOS config and the space has been added to the pool). */ uint64_t mc_groups; /* * Toggle to enable/disable the allocation throttle. */ boolean_t mc_alloc_throttle_enabled; /* * The allocation throttle works on a reservation system. Whenever * an asynchronous zio wants to perform an allocation it must * first reserve the number of blocks that it wants to allocate. * If there aren't sufficient slots available for the pending zio * then that I/O is throttled until more slots free up. The current * number of reserved allocations is maintained by the mc_alloc_slots * refcount. The mc_alloc_max_slots value determines the maximum * number of allocations that the system allows. Gang blocks are * allowed to reserve slots even if we've reached the maximum * number of allocations allowed. */ uint64_t *mc_alloc_max_slots; zfs_refcount_t *mc_alloc_slots; uint64_t mc_alloc_groups; /* # of allocatable groups */ uint64_t mc_alloc; /* total allocated space */ uint64_t mc_deferred; /* total deferred frees */ uint64_t mc_space; /* total space (alloc + free) */ uint64_t mc_dspace; /* total deflated space */ uint64_t mc_histogram[RANGE_TREE_HISTOGRAM_SIZE]; /* * List of all loaded metaslabs in the class, sorted in order of most * recent use. */ multilist_t *mc_metaslab_txg_list; }; /* * Metaslab groups encapsulate all the allocatable regions (i.e. metaslabs) * of a top-level vdev. They are linked togther to form a circular linked * list and can belong to only one metaslab class. Metaslab groups may become * ineligible for allocations for a number of reasons such as limited free * space, fragmentation, or going offline. When this happens the allocator will * simply find the next metaslab group in the linked list and attempt * to allocate from that group instead. */ struct metaslab_group { kmutex_t mg_lock; metaslab_t **mg_primaries; metaslab_t **mg_secondaries; avl_tree_t mg_metaslab_tree; uint64_t mg_aliquot; boolean_t mg_allocatable; /* can we allocate? */ uint64_t mg_ms_ready; /* * A metaslab group is considered to be initialized only after * we have updated the MOS config and added the space to the pool. * We only allow allocation attempts to a metaslab group if it * has been initialized. */ boolean_t mg_initialized; uint64_t mg_free_capacity; /* percentage free */ int64_t mg_bias; int64_t mg_activation_count; metaslab_class_t *mg_class; vdev_t *mg_vd; taskq_t *mg_taskq; metaslab_group_t *mg_prev; metaslab_group_t *mg_next; /* * In order for the allocation throttle to function properly, we cannot * have too many IOs going to each disk by default; the throttle * operates by allocating more work to disks that finish quickly, so * allocating larger chunks to each disk reduces its effectiveness. * However, if the number of IOs going to each allocator is too small, * we will not perform proper aggregation at the vdev_queue layer, * also resulting in decreased performance. Therefore, we will use a * ramp-up strategy. * * Each allocator in each metaslab group has a current queue depth * (mg_alloc_queue_depth[allocator]) and a current max queue depth * (mg_cur_max_alloc_queue_depth[allocator]), and each metaslab group * has an absolute max queue depth (mg_max_alloc_queue_depth). We * add IOs to an allocator until the mg_alloc_queue_depth for that * allocator hits the cur_max. Every time an IO completes for a given * allocator on a given metaslab group, we increment its cur_max until * it reaches mg_max_alloc_queue_depth. The cur_max resets every txg to * help protect against disks that decrease in performance over time. * * It's possible for an allocator to handle more allocations than * its max. This can occur when gang blocks are required or when other * groups are unable to handle their share of allocations. */ uint64_t mg_max_alloc_queue_depth; uint64_t *mg_cur_max_alloc_queue_depth; zfs_refcount_t *mg_alloc_queue_depth; int mg_allocators; /* * A metalab group that can no longer allocate the minimum block * size will set mg_no_free_space. Once a metaslab group is out * of space then its share of work must be distributed to other * groups. */ boolean_t mg_no_free_space; uint64_t mg_allocations; uint64_t mg_failed_allocations; uint64_t mg_fragmentation; uint64_t mg_histogram[RANGE_TREE_HISTOGRAM_SIZE]; int mg_ms_disabled; boolean_t mg_disabled_updating; kmutex_t mg_ms_disabled_lock; kcondvar_t mg_ms_disabled_cv; }; /* * This value defines the number of elements in the ms_lbas array. The value * of 64 was chosen as it covers all power of 2 buckets up to UINT64_MAX. * This is the equivalent of highbit(UINT64_MAX). */ #define MAX_LBAS 64 /* * Each metaslab maintains a set of in-core trees to track metaslab * operations. The in-core free tree (ms_allocatable) contains the list of * free segments which are eligible for allocation. As blocks are * allocated, the allocated segment are removed from the ms_allocatable and * added to a per txg allocation tree (ms_allocating). As blocks are * freed, they are added to the free tree (ms_freeing). These trees * allow us to process all allocations and frees in syncing context * where it is safe to update the on-disk space maps. An additional set * of in-core trees is maintained to track deferred frees * (ms_defer). Once a block is freed it will move from the * ms_freed to the ms_defer tree. A deferred free means that a block * has been freed but cannot be used by the pool until TXG_DEFER_SIZE * transactions groups later. For example, a block that is freed in txg * 50 will not be available for reallocation until txg 52 (50 + * TXG_DEFER_SIZE). This provides a safety net for uberblock rollback. * A pool could be safely rolled back TXG_DEFERS_SIZE transactions * groups and ensure that no block has been reallocated. * * The simplified transition diagram looks like this: * * * ALLOCATE * | * V * free segment (ms_allocatable) -> ms_allocating[4] -> (write to space map) * ^ * | ms_freeing <--- FREE * | | * | v * | ms_freed * | | * +-------- ms_defer[2] <-------+-------> (write to space map) * * * Each metaslab's space is tracked in a single space map in the MOS, * which is only updated in syncing context. Each time we sync a txg, * we append the allocs and frees from that txg to the space map. The * pool space is only updated once all metaslabs have finished syncing. * * To load the in-core free tree we read the space map from disk. This * object contains a series of alloc and free records that are combined * to make up the list of all free segments in this metaslab. These * segments are represented in-core by the ms_allocatable and are stored * in an AVL tree. * * As the space map grows (as a result of the appends) it will * eventually become space-inefficient. When the metaslab's in-core * free tree is zfs_condense_pct/100 times the size of the minimal * on-disk representation, we rewrite it in its minimized form. If a * metaslab needs to condense then we must set the ms_condensing flag to * ensure that allocations are not performed on the metaslab that is * being written. */ struct metaslab { /* * This is the main lock of the metaslab and its purpose is to * coordinate our allocations and frees [e.g metaslab_block_alloc(), * metaslab_free_concrete(), ..etc] with our various syncing * procedures [e.g. metaslab_sync(), metaslab_sync_done(), ..etc]. * * The lock is also used during some miscellaneous operations like * using the metaslab's histogram for the metaslab group's histogram * aggregation, or marking the metaslab for initialization. */ kmutex_t ms_lock; /* * Acquired together with the ms_lock whenever we expect to * write to metaslab data on-disk (i.e flushing entries to * the metaslab's space map). It helps coordinate readers of * the metaslab's space map [see spa_vdev_remove_thread()] * with writers [see metaslab_sync() or metaslab_flush()]. * * Note that metaslab_load(), even though a reader, uses * a completely different mechanism to deal with the reading * of the metaslab's space map based on ms_synced_length. That * said, the function still uses the ms_sync_lock after it * has read the ms_sm [see relevant comment in metaslab_load() * as to why]. */ kmutex_t ms_sync_lock; kcondvar_t ms_load_cv; space_map_t *ms_sm; uint64_t ms_id; uint64_t ms_start; uint64_t ms_size; uint64_t ms_fragmentation; range_tree_t *ms_allocating[TXG_SIZE]; range_tree_t *ms_allocatable; uint64_t ms_allocated_this_txg; uint64_t ms_allocating_total; /* * The following range trees are accessed only from syncing context. * ms_free*tree only have entries while syncing, and are empty * between syncs. */ range_tree_t *ms_freeing; /* to free this syncing txg */ range_tree_t *ms_freed; /* already freed this syncing txg */ range_tree_t *ms_defer[TXG_DEFER_SIZE]; range_tree_t *ms_checkpointing; /* to add to the checkpoint */ /* * The ms_trim tree is the set of allocatable segments which are * eligible for trimming. (When the metaslab is loaded, it's a * subset of ms_allocatable.) It's kept in-core as long as the * autotrim property is set and is not vacated when the metaslab * is unloaded. Its purpose is to aggregate freed ranges to * facilitate efficient trimming. */ range_tree_t *ms_trim; boolean_t ms_condensing; /* condensing? */ boolean_t ms_condense_wanted; /* * The number of consumers which have disabled the metaslab. */ uint64_t ms_disabled; /* * We must always hold the ms_lock when modifying ms_loaded * and ms_loading. */ boolean_t ms_loaded; boolean_t ms_loading; kcondvar_t ms_flush_cv; boolean_t ms_flushing; /* * The following histograms count entries that are in the * metaslab's space map (and its histogram) but are not in * ms_allocatable yet, because they are in ms_freed, ms_freeing, * or ms_defer[]. * * When the metaslab is not loaded, its ms_weight needs to * reflect what is allocatable (i.e. what will be part of * ms_allocatable if it is loaded). The weight is computed from * the spacemap histogram, but that includes ranges that are * not yet allocatable (because they are in ms_freed, * ms_freeing, or ms_defer[]). Therefore, when calculating the * weight, we need to remove those ranges. * * The ranges in the ms_freed and ms_defer[] range trees are all * present in the spacemap. However, the spacemap may have * multiple entries to represent a contiguous range, because it * is written across multiple sync passes, but the changes of * all sync passes are consolidated into the range trees. * Adjacent ranges that are freed in different sync passes of * one txg will be represented separately (as 2 or more entries) * in the space map (and its histogram), but these adjacent * ranges will be consolidated (represented as one entry) in the * ms_freed/ms_defer[] range trees (and their histograms). * * When calculating the weight, we can not simply subtract the * range trees' histograms from the spacemap's histogram, * because the range trees' histograms may have entries in * higher buckets than the spacemap, due to consolidation. * Instead we must subtract the exact entries that were added to * the spacemap's histogram. ms_synchist and ms_deferhist[] * represent these exact entries, so we can subtract them from * the spacemap's histogram when calculating ms_weight. * * ms_synchist represents the same ranges as ms_freeing + * ms_freed, but without consolidation across sync passes. * * ms_deferhist[i] represents the same ranges as ms_defer[i], * but without consolidation across sync passes. */ uint64_t ms_synchist[SPACE_MAP_HISTOGRAM_SIZE]; uint64_t ms_deferhist[TXG_DEFER_SIZE][SPACE_MAP_HISTOGRAM_SIZE]; /* * Tracks the exact amount of allocated space of this metaslab * (and specifically the metaslab's space map) up to the most * recently completed sync pass [see usage in metaslab_sync()]. */ uint64_t ms_allocated_space; int64_t ms_deferspace; /* sum of ms_defermap[] space */ uint64_t ms_weight; /* weight vs. others in group */ uint64_t ms_activation_weight; /* activation weight */ /* * Track of whenever a metaslab is selected for loading or allocation. * We use this value to determine how long the metaslab should * stay cached. */ uint64_t ms_selected_txg; /* * ms_load/unload_time can be used for performance monitoring * (e.g. by dtrace or mdb). */ hrtime_t ms_load_time; /* time last loaded */ hrtime_t ms_unload_time; /* time last unloaded */ hrtime_t ms_selected_time; /* time last allocated from */ uint64_t ms_alloc_txg; /* last successful alloc (debug only) */ uint64_t ms_max_size; /* maximum allocatable size */ /* * -1 if it's not active in an allocator, otherwise set to the allocator * this metaslab is active for. */ int ms_allocator; boolean_t ms_primary; /* Only valid if ms_allocator is not -1 */ /* * The metaslab block allocators can optionally use a size-ordered * range tree and/or an array of LBAs. Not all allocators use * this functionality. The ms_allocatable_by_size should always * contain the same number of segments as the ms_allocatable. The * only difference is that the ms_allocatable_by_size is ordered by * segment sizes. */ zfs_btree_t ms_allocatable_by_size; zfs_btree_t ms_unflushed_frees_by_size; uint64_t ms_lbas[MAX_LBAS]; metaslab_group_t *ms_group; /* metaslab group */ avl_node_t ms_group_node; /* node in metaslab group tree */ txg_node_t ms_txg_node; /* per-txg dirty metaslab links */ avl_node_t ms_spa_txg_node; /* node in spa_metaslabs_by_txg */ /* * Node in metaslab class's selected txg list */ multilist_node_t ms_class_txg_node; /* * Allocs and frees that are committed to the vdev log spacemap but * not yet to this metaslab's spacemap. */ range_tree_t *ms_unflushed_allocs; range_tree_t *ms_unflushed_frees; /* * We have flushed entries up to but not including this TXG. In * other words, all changes from this TXG and onward should not * be in this metaslab's space map and must be read from the * log space maps. */ uint64_t ms_unflushed_txg; /* updated every time we are done syncing the metaslab's space map */ uint64_t ms_synced_length; boolean_t ms_new; }; typedef struct metaslab_unflushed_phys { /* on-disk counterpart of ms_unflushed_txg */ uint64_t msp_unflushed_txg; } metaslab_unflushed_phys_t; #ifdef __cplusplus } #endif #endif /* _SYS_METASLAB_IMPL_H */
