diff options
Diffstat (limited to 'uts/common/fs/zfs/sys/metaslab_impl.h')
| -rw-r--r-- | uts/common/fs/zfs/sys/metaslab_impl.h | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/uts/common/fs/zfs/sys/metaslab_impl.h b/uts/common/fs/zfs/sys/metaslab_impl.h index a2c8e6051772..f8d36f38f7b7 100644 --- a/uts/common/fs/zfs/sys/metaslab_impl.h +++ b/uts/common/fs/zfs/sys/metaslab_impl.h @@ -340,8 +340,34 @@ struct metaslab_group { * 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()]. + * + * 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; @@ -351,6 +377,7 @@ struct metaslab { range_tree_t *ms_allocating[TXG_SIZE]; range_tree_t *ms_allocatable; + uint64_t ms_allocated_this_txg; /* * The following range trees are accessed only from syncing context. @@ -375,6 +402,55 @@ struct metaslab { boolean_t ms_loaded; boolean_t ms_loading; + /* + * 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 */ @@ -411,6 +487,9 @@ struct metaslab { 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; }; |