*/
/*
- * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2019 by Delphix. All rights reserved.
*/
#ifndef _SYS_METASLAB_IMPL_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
* allowed to reserve slots even if we've reached the maximum
* number of allocations allowed.
*/
- uint64_t mc_alloc_max_slots;
- refcount_t mc_alloc_slots;
+ uint64_t *mc_alloc_max_slots;
+ zfs_refcount_t *mc_alloc_slots;
uint64_t mc_alloc_groups; /* # of allocatable groups */
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;
};
+/*
+ * Per-allocator data structure.
+ */
+typedef struct metaslab_group_allocator {
+ uint64_t mga_cur_max_alloc_queue_depth;
+ zfs_refcount_t mga_alloc_queue_depth;
+ metaslab_t *mga_primary;
+ metaslab_t *mga_secondary;
+} metaslab_group_allocator_t;
+
/*
* Metaslab groups encapsulate all the allocatable regions (i.e. metaslabs)
* of a top-level vdev. They are linked together to form a circular linked
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
metaslab_group_t *mg_next;
/*
- * Each metaslab group can handle mg_max_alloc_queue_depth allocations
- * which are tracked by mg_alloc_queue_depth. It's possible for a
- * metaslab group 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.
+ * 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;
- refcount_t mg_alloc_queue_depth;
-
+ int mg_allocators;
+ metaslab_group_allocator_t *mg_allocator; /* array */
/*
* A metalab group that can no longer allocate the minimum block
* size will set mg_no_free_space. Once a metaslab group is out
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;
};
/*
#define MAX_LBAS 64
/*
- * Each metaslab maintains a set of in-core trees to track metaslab operations.
- * The in-core free tree (ms_tree) contains the current list of free segments.
- * As blocks are allocated, the allocated segment are removed from the ms_tree
- * and added to a per txg allocation tree (ms_alloctree). As blocks are freed,
- * they are added to the per txg free tree (ms_freetree). These per txg
- * trees allow us to process all allocations and frees in syncing context
- * where it is safe to update the on-disk space maps. One additional in-core
- * tree is maintained to track deferred frees (ms_defertree). Once a block
- * is freed it will move from the ms_freetree to the ms_defertree. 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.
+ * 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_tree) --------> ms_alloctree ----> (write to space map)
+ * free segment (ms_allocatable) -> ms_allocating[4] -> (write to space map)
* ^
- * |
- * | ms_freetree <--- FREE
- * | |
- * | |
- * | |
- * +----------- ms_defertree <-------+---------> (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.
+ * 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_tree and are stored in an
- * AVL tree.
+ * 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.
+ * 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;
- metaslab_ops_t *ms_ops;
uint64_t ms_id;
uint64_t ms_start;
uint64_t ms_size;
uint64_t ms_fragmentation;
- range_tree_t *ms_alloctree[TXG_SIZE];
- range_tree_t *ms_freetree[TXG_SIZE];
- range_tree_t *ms_defertree[TXG_DEFER_SIZE];
- range_tree_t *ms_tree;
+ 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_access_txg;
+ 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_size_tree should always contain the
- * same number of segments as the ms_tree. The only difference
- * is that the ms_size_tree is ordered by segment sizes.
+ * 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.
*/
- avl_tree_t ms_size_tree;
+ 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
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