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| author | Marko Mäkelä <marko.makela@mariadb.com> | 2020-06-18 13:38:30 +0300 |
|---|---|---|
| committer | Marko Mäkelä <marko.makela@mariadb.com> | 2020-06-18 14:16:01 +0300 |
| commit | 5155a300fab85e97217c75e3ba3c3ce78082dd8a (patch) | |
| tree | 7180cc802900bbf2c5328835d3de39e78c469615 /storage/innobase/include/sync0sync.h | |
| parent | cfd3d70ccbbfcf3fdec034be446317741dfae824 (diff) | |
| download | mariadb-git-5155a300fab85e97217c75e3ba3c3ce78082dd8a.tar.gz | |
MDEV-22871: Reduce InnoDB buf_pool.page_hash contention
The rw_lock_s_lock() calls for the buf_pool.page_hash became a
clear bottleneck after MDEV-15053 reduced the contention on
buf_pool.mutex. We will replace that use of rw_lock_t with a
special implementation that is optimized for memory bus traffic.
The hash_table_locks instrumentation will be removed.
buf_pool_t::page_hash: Use a special implementation whose API is
compatible with hash_table_t, and store the custom rw-locks
directly in buf_pool.page_hash.array, intentionally sharing
cache lines with the hash table pointers.
rw_lock: A low-level rw-lock implementation based on std::atomic<uint32_t>
where read_trylock() becomes a simple fetch_add(1).
buf_pool_t::page_hash_latch: The special of rw_lock for the page_hash.
buf_pool_t::page_hash_latch::read_lock(): Assert that buf_pool.mutex
is not being held by the caller.
buf_pool_t::page_hash_latch::write_lock() may be called while not holding
buf_pool.mutex. buf_pool_t::watch_set() is such a caller.
buf_pool_t::page_hash_latch::read_lock_wait(),
page_hash_latch::write_lock_wait(): The spin loops.
These will obey the global parameters innodb_sync_spin_loops and
innodb_sync_spin_wait_delay.
buf_pool_t::freed_page_hash: A singly linked list of copies of
buf_pool.page_hash that ever existed. The fact that we never
free any buf_pool.page_hash.array guarantees that all
page_hash_latch that ever existed will remain valid until shutdown.
buf_pool_t::resize_hash(): Replaces buf_pool_resize_hash().
Prepend a shallow copy of the old page_hash to freed_page_hash.
buf_pool_t::page_hash_table::n_cells: Declare as Atomic_relaxed.
buf_pool_t::page_hash_table::lock(): Explain what prevents a
race condition with buf_pool_t::resize_hash().
Diffstat (limited to 'storage/innobase/include/sync0sync.h')
| -rw-r--r-- | storage/innobase/include/sync0sync.h | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/storage/innobase/include/sync0sync.h b/storage/innobase/include/sync0sync.h index 7eb8250b63d..c63fedb43ee 100644 --- a/storage/innobase/include/sync0sync.h +++ b/storage/innobase/include/sync0sync.h @@ -126,7 +126,6 @@ extern mysql_pfs_key_t index_tree_rw_lock_key; extern mysql_pfs_key_t index_online_log_key; extern mysql_pfs_key_t dict_table_stats_key; extern mysql_pfs_key_t trx_sys_rw_lock_key; -extern mysql_pfs_key_t hash_table_locks_key; #endif /* UNIV_PFS_RWLOCK */ /** Prints info of the sync system. |