514 lines
20 KiB
C
514 lines
20 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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*/
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/*
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* Copyright (c) 2011, 2018 by Delphix. All rights reserved.
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*/
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#ifndef _SYS_METASLAB_IMPL_H
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#define _SYS_METASLAB_IMPL_H
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#include <sys/metaslab.h>
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#include <sys/space_map.h>
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#include <sys/range_tree.h>
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#include <sys/vdev.h>
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#include <sys/txg.h>
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#include <sys/avl.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* Metaslab allocation tracing record.
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*/
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typedef struct metaslab_alloc_trace {
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list_node_t mat_list_node;
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metaslab_group_t *mat_mg;
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metaslab_t *mat_msp;
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uint64_t mat_size;
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uint64_t mat_weight;
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uint32_t mat_dva_id;
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uint64_t mat_offset;
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int mat_allocator;
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} metaslab_alloc_trace_t;
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/*
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* Used by the metaslab allocation tracing facility to indicate
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* error conditions. These errors are stored to the offset member
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* of the metaslab_alloc_trace_t record and displayed by mdb.
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*/
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typedef enum trace_alloc_type {
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TRACE_ALLOC_FAILURE = -1ULL,
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TRACE_TOO_SMALL = -2ULL,
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TRACE_FORCE_GANG = -3ULL,
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TRACE_NOT_ALLOCATABLE = -4ULL,
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TRACE_GROUP_FAILURE = -5ULL,
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TRACE_ENOSPC = -6ULL,
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TRACE_CONDENSING = -7ULL,
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TRACE_VDEV_ERROR = -8ULL,
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TRACE_DISABLED = -9ULL,
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} trace_alloc_type_t;
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#define METASLAB_WEIGHT_PRIMARY (1ULL << 63)
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#define METASLAB_WEIGHT_SECONDARY (1ULL << 62)
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#define METASLAB_WEIGHT_CLAIM (1ULL << 61)
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#define METASLAB_WEIGHT_TYPE (1ULL << 60)
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#define METASLAB_ACTIVE_MASK \
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(METASLAB_WEIGHT_PRIMARY | METASLAB_WEIGHT_SECONDARY | \
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METASLAB_WEIGHT_CLAIM)
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/*
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* The metaslab weight is used to encode the amount of free space in a
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* metaslab, such that the "best" metaslab appears first when sorting the
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* metaslabs by weight. The weight (and therefore the "best" metaslab) can
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* be determined in two different ways: by computing a weighted sum of all
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* the free space in the metaslab (a space based weight) or by counting only
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* the free segments of the largest size (a segment based weight). We prefer
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* the segment based weight because it reflects how the free space is
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* comprised, but we cannot always use it -- legacy pools do not have the
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* space map histogram information necessary to determine the largest
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* contiguous regions. Pools that have the space map histogram determine
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* the segment weight by looking at each bucket in the histogram and
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* determining the free space whose size in bytes is in the range:
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* [2^i, 2^(i+1))
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* We then encode the largest index, i, that contains regions into the
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* segment-weighted value.
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*
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* Space-based weight:
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*
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* 64 56 48 40 32 24 16 8 0
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* +-------+-------+-------+-------+-------+-------+-------+-------+
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* |PSC1| weighted-free space |
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* +-------+-------+-------+-------+-------+-------+-------+-------+
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*
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* PS - indicates primary and secondary activation
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* C - indicates activation for claimed block zio
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* space - the fragmentation-weighted space
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*
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* Segment-based weight:
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*
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* 64 56 48 40 32 24 16 8 0
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* +-------+-------+-------+-------+-------+-------+-------+-------+
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* |PSC0| idx| count of segments in region |
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* +-------+-------+-------+-------+-------+-------+-------+-------+
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*
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* PS - indicates primary and secondary activation
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* C - indicates activation for claimed block zio
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* idx - index for the highest bucket in the histogram
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* count - number of segments in the specified bucket
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*/
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#define WEIGHT_GET_ACTIVE(weight) BF64_GET((weight), 61, 3)
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#define WEIGHT_SET_ACTIVE(weight, x) BF64_SET((weight), 61, 3, x)
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#define WEIGHT_IS_SPACEBASED(weight) \
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((weight) == 0 || BF64_GET((weight), 60, 1))
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#define WEIGHT_SET_SPACEBASED(weight) BF64_SET((weight), 60, 1, 1)
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/*
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* These macros are only applicable to segment-based weighting.
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*/
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#define WEIGHT_GET_INDEX(weight) BF64_GET((weight), 54, 6)
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#define WEIGHT_SET_INDEX(weight, x) BF64_SET((weight), 54, 6, x)
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#define WEIGHT_GET_COUNT(weight) BF64_GET((weight), 0, 54)
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#define WEIGHT_SET_COUNT(weight, x) BF64_SET((weight), 0, 54, x)
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/*
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* A metaslab class encompasses a category of allocatable top-level vdevs.
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* Each top-level vdev is associated with a metaslab group which defines
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* the allocatable region for that vdev. Examples of these categories include
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* "normal" for data block allocations (i.e. main pool allocations) or "log"
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* for allocations designated for intent log devices (i.e. slog devices).
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* When a block allocation is requested from the SPA it is associated with a
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* metaslab_class_t, and only top-level vdevs (i.e. metaslab groups) belonging
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* to the class can be used to satisfy that request. Allocations are done
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* by traversing the metaslab groups that are linked off of the mc_rotor field.
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* This rotor points to the next metaslab group where allocations will be
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* attempted. Allocating a block is a 3 step process -- select the metaslab
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* group, select the metaslab, and then allocate the block. The metaslab
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* class defines the low-level block allocator that will be used as the
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* final step in allocation. These allocators are pluggable allowing each class
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* to use a block allocator that best suits that class.
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*/
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struct metaslab_class {
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kmutex_t mc_lock;
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spa_t *mc_spa;
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metaslab_group_t *mc_rotor;
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metaslab_ops_t *mc_ops;
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uint64_t mc_aliquot;
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/*
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* Track the number of metaslab groups that have been initialized
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* and can accept allocations. An initialized metaslab group is
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* one has been completely added to the config (i.e. we have
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* updated the MOS config and the space has been added to the pool).
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*/
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uint64_t mc_groups;
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/*
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* Toggle to enable/disable the allocation throttle.
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*/
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boolean_t mc_alloc_throttle_enabled;
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/*
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* The allocation throttle works on a reservation system. Whenever
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* an asynchronous zio wants to perform an allocation it must
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* first reserve the number of blocks that it wants to allocate.
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* If there aren't sufficient slots available for the pending zio
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* then that I/O is throttled until more slots free up. The current
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* number of reserved allocations is maintained by the mc_alloc_slots
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* refcount. The mc_alloc_max_slots value determines the maximum
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* number of allocations that the system allows. Gang blocks are
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* allowed to reserve slots even if we've reached the maximum
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* number of allocations allowed.
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*/
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uint64_t *mc_alloc_max_slots;
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zfs_refcount_t *mc_alloc_slots;
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uint64_t mc_alloc_groups; /* # of allocatable groups */
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uint64_t mc_alloc; /* total allocated space */
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uint64_t mc_deferred; /* total deferred frees */
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uint64_t mc_space; /* total space (alloc + free) */
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uint64_t mc_dspace; /* total deflated space */
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uint64_t mc_histogram[RANGE_TREE_HISTOGRAM_SIZE];
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};
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/*
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* Metaslab groups encapsulate all the allocatable regions (i.e. metaslabs)
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* of a top-level vdev. They are linked together to form a circular linked
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* list and can belong to only one metaslab class. Metaslab groups may become
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* ineligible for allocations for a number of reasons such as limited free
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* space, fragmentation, or going offline. When this happens the allocator will
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* simply find the next metaslab group in the linked list and attempt
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* to allocate from that group instead.
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*/
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struct metaslab_group {
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kmutex_t mg_lock;
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metaslab_t **mg_primaries;
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metaslab_t **mg_secondaries;
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avl_tree_t mg_metaslab_tree;
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uint64_t mg_aliquot;
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boolean_t mg_allocatable; /* can we allocate? */
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uint64_t mg_ms_ready;
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/*
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* A metaslab group is considered to be initialized only after
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* we have updated the MOS config and added the space to the pool.
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* We only allow allocation attempts to a metaslab group if it
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* has been initialized.
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*/
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boolean_t mg_initialized;
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uint64_t mg_free_capacity; /* percentage free */
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int64_t mg_bias;
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int64_t mg_activation_count;
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metaslab_class_t *mg_class;
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vdev_t *mg_vd;
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taskq_t *mg_taskq;
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metaslab_group_t *mg_prev;
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metaslab_group_t *mg_next;
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/*
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* In order for the allocation throttle to function properly, we cannot
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* have too many IOs going to each disk by default; the throttle
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* operates by allocating more work to disks that finish quickly, so
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* allocating larger chunks to each disk reduces its effectiveness.
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* However, if the number of IOs going to each allocator is too small,
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* we will not perform proper aggregation at the vdev_queue layer,
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* also resulting in decreased performance. Therefore, we will use a
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* ramp-up strategy.
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*
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* Each allocator in each metaslab group has a current queue depth
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* (mg_alloc_queue_depth[allocator]) and a current max queue depth
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* (mg_cur_max_alloc_queue_depth[allocator]), and each metaslab group
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* has an absolute max queue depth (mg_max_alloc_queue_depth). We
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* add IOs to an allocator until the mg_alloc_queue_depth for that
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* allocator hits the cur_max. Every time an IO completes for a given
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* allocator on a given metaslab group, we increment its cur_max until
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* it reaches mg_max_alloc_queue_depth. The cur_max resets every txg to
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* help protect against disks that decrease in performance over time.
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*
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* It's possible for an allocator to handle more allocations than
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* its max. This can occur when gang blocks are required or when other
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* groups are unable to handle their share of allocations.
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*/
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uint64_t mg_max_alloc_queue_depth;
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uint64_t *mg_cur_max_alloc_queue_depth;
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zfs_refcount_t *mg_alloc_queue_depth;
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int mg_allocators;
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/*
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* A metalab group that can no longer allocate the minimum block
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* size will set mg_no_free_space. Once a metaslab group is out
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* of space then its share of work must be distributed to other
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* groups.
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*/
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boolean_t mg_no_free_space;
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uint64_t mg_allocations;
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uint64_t mg_failed_allocations;
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uint64_t mg_fragmentation;
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uint64_t mg_histogram[RANGE_TREE_HISTOGRAM_SIZE];
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int mg_ms_disabled;
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boolean_t mg_disabled_updating;
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kmutex_t mg_ms_disabled_lock;
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kcondvar_t mg_ms_disabled_cv;
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};
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/*
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* This value defines the number of elements in the ms_lbas array. The value
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* of 64 was chosen as it covers all power of 2 buckets up to UINT64_MAX.
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* This is the equivalent of highbit(UINT64_MAX).
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*/
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#define MAX_LBAS 64
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/*
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* Each metaslab maintains a set of in-core trees to track metaslab
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* operations. The in-core free tree (ms_allocatable) contains the list of
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* free segments which are eligible for allocation. As blocks are
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* allocated, the allocated segment are removed from the ms_allocatable and
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* added to a per txg allocation tree (ms_allocating). As blocks are
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* freed, they are added to the free tree (ms_freeing). These trees
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* allow us to process all allocations and frees in syncing context
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* where it is safe to update the on-disk space maps. An additional set
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* of in-core trees is maintained to track deferred frees
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* (ms_defer). Once a block is freed it will move from the
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* ms_freed to the ms_defer tree. A deferred free means that a block
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* has been freed but cannot be used by the pool until TXG_DEFER_SIZE
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* transactions groups later. For example, a block that is freed in txg
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* 50 will not be available for reallocation until txg 52 (50 +
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* TXG_DEFER_SIZE). This provides a safety net for uberblock rollback.
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* A pool could be safely rolled back TXG_DEFERS_SIZE transactions
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* groups and ensure that no block has been reallocated.
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*
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* The simplified transition diagram looks like this:
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*
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*
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* ALLOCATE
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* |
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* V
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* free segment (ms_allocatable) -> ms_allocating[4] -> (write to space map)
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* ^
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* | ms_freeing <--- FREE
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* | |
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* | v
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* | ms_freed
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* | |
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* +-------- ms_defer[2] <-------+-------> (write to space map)
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*
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*
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* Each metaslab's space is tracked in a single space map in the MOS,
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* which is only updated in syncing context. Each time we sync a txg,
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* we append the allocs and frees from that txg to the space map. The
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* pool space is only updated once all metaslabs have finished syncing.
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*
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* To load the in-core free tree we read the space map from disk. This
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* object contains a series of alloc and free records that are combined
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* to make up the list of all free segments in this metaslab. These
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* segments are represented in-core by the ms_allocatable and are stored
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* in an AVL tree.
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*
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* As the space map grows (as a result of the appends) it will
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* eventually become space-inefficient. When the metaslab's in-core
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* free tree is zfs_condense_pct/100 times the size of the minimal
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* on-disk representation, we rewrite it in its minimized form. If a
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* metaslab needs to condense then we must set the ms_condensing flag to
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* ensure that allocations are not performed on the metaslab that is
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* being written.
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*/
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struct metaslab {
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/*
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* This is the main lock of the metaslab and its purpose is to
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* coordinate our allocations and frees [e.g metaslab_block_alloc(),
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* metaslab_free_concrete(), ..etc] with our various syncing
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* procedures [e.g. metaslab_sync(), metaslab_sync_done(), ..etc].
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*
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* The lock is also used during some miscellaneous operations like
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* using the metaslab's histogram for the metaslab group's histogram
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* aggregation, or marking the metaslab for initialization.
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*/
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kmutex_t ms_lock;
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/*
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* Acquired together with the ms_lock whenever we expect to
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* write to metaslab data on-disk (i.e flushing entries to
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* the metaslab's space map). It helps coordinate readers of
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* the metaslab's space map [see spa_vdev_remove_thread()]
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* with writers [see metaslab_sync()].
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*
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* Note that metaslab_load(), even though a reader, uses
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* a completely different mechanism to deal with the reading
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* of the metaslab's space map based on ms_synced_length. That
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* said, the function still uses the ms_sync_lock after it
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* has read the ms_sm [see relevant comment in metaslab_load()
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* as to why].
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*/
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kmutex_t ms_sync_lock;
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kcondvar_t ms_load_cv;
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space_map_t *ms_sm;
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uint64_t ms_id;
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uint64_t ms_start;
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uint64_t ms_size;
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uint64_t ms_fragmentation;
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range_tree_t *ms_allocating[TXG_SIZE];
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range_tree_t *ms_allocatable;
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uint64_t ms_allocated_this_txg;
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/*
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* The following range trees are accessed only from syncing context.
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* ms_free*tree only have entries while syncing, and are empty
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* between syncs.
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*/
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range_tree_t *ms_freeing; /* to free this syncing txg */
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range_tree_t *ms_freed; /* already freed this syncing txg */
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range_tree_t *ms_defer[TXG_DEFER_SIZE];
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range_tree_t *ms_checkpointing; /* to add to the checkpoint */
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/*
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* The ms_trim tree is the set of allocatable segments which are
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* eligible for trimming. (When the metaslab is loaded, it's a
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* subset of ms_allocatable.) It's kept in-core as long as the
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* autotrim property is set and is not vacated when the metaslab
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* is unloaded. Its purpose is to aggregate freed ranges to
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* facilitate efficient trimming.
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*/
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range_tree_t *ms_trim;
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boolean_t ms_condensing; /* condensing? */
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boolean_t ms_condense_wanted;
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uint64_t ms_condense_checked_txg;
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/*
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* The number of consumers which have disabled the metaslab.
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*/
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uint64_t ms_disabled;
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/*
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* We must always hold the ms_lock when modifying ms_loaded
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* and ms_loading.
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*/
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boolean_t ms_loaded;
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boolean_t ms_loading;
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/*
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* The following histograms count entries that are in the
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* metaslab's space map (and its histogram) but are not in
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* ms_allocatable yet, because they are in ms_freed, ms_freeing,
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* or ms_defer[].
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*
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* When the metaslab is not loaded, its ms_weight needs to
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* reflect what is allocatable (i.e. what will be part of
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* ms_allocatable if it is loaded). The weight is computed from
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* the spacemap histogram, but that includes ranges that are
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* not yet allocatable (because they are in ms_freed,
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* ms_freeing, or ms_defer[]). Therefore, when calculating the
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* weight, we need to remove those ranges.
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*
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* The ranges in the ms_freed and ms_defer[] range trees are all
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* present in the spacemap. However, the spacemap may have
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* multiple entries to represent a contiguous range, because it
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* is written across multiple sync passes, but the changes of
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* all sync passes are consolidated into the range trees.
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* Adjacent ranges that are freed in different sync passes of
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* one txg will be represented separately (as 2 or more entries)
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* in the space map (and its histogram), but these adjacent
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* ranges will be consolidated (represented as one entry) in the
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* ms_freed/ms_defer[] range trees (and their histograms).
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*
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* When calculating the weight, we can not simply subtract the
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* range trees' histograms from the spacemap's histogram,
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* because the range trees' histograms may have entries in
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* higher buckets than the spacemap, due to consolidation.
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* Instead we must subtract the exact entries that were added to
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* the spacemap's histogram. ms_synchist and ms_deferhist[]
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* represent these exact entries, so we can subtract them from
|
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* the spacemap's histogram when calculating ms_weight.
|
|
*
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* ms_synchist represents the same ranges as ms_freeing +
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* ms_freed, but without consolidation across sync passes.
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*
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* ms_deferhist[i] represents the same ranges as ms_defer[i],
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* but without consolidation across sync passes.
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|
*/
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uint64_t ms_synchist[SPACE_MAP_HISTOGRAM_SIZE];
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uint64_t ms_deferhist[TXG_DEFER_SIZE][SPACE_MAP_HISTOGRAM_SIZE];
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|
|
|
/*
|
|
* Tracks the exact amount of allocated space of this metaslab
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|
* (and specifically the metaslab's space map) up to the most
|
|
* recently completed sync pass [see usage in metaslab_sync()].
|
|
*/
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|
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;
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|
|
|
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.
|
|
*/
|
|
avl_tree_t ms_allocatable_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 */
|
|
|
|
/* updated every time we are done syncing the metaslab's space map */
|
|
uint64_t ms_synced_length;
|
|
|
|
boolean_t ms_new;
|
|
};
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif /* _SYS_METASLAB_IMPL_H */
|