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	a3d0d5fc33
	
	
	
		
			
			This is a 10.5 backport from 10.6
commit 9593cccf28.
Adaptive flushing is enabled by setting innodb_max_dirty_pages_pct_lwm>0
(not default) and innodb_adaptive_flushing=ON (default).
There is also the parameter innodb_adaptive_flushing_lwm
(default: 10 per cent of the log capacity). It should enable some
adaptive flushing even when innodb_max_dirty_pages_pct_lwm=0.
That is not being changed here.
This idea was first presented by Inaam Rana several years ago,
and I discussed it with Jean-François Gagné at FOSDEM 2023.
buf_flush_page_cleaner(): When we are not near the log capacity limit
(neither buf_flush_async_lsn nor buf_flush_sync_lsn are set),
also try to move clean blocks from the buf_pool.LRU list to buf_pool.free
or initiate writes (but not the eviction) of dirty blocks, until
the remaining I/O capacity has been consumed.
buf_flush_LRU_list_batch(): Add the parameter bool evict, to specify
whether dirty least recently used pages (from buf_pool.LRU) should
be evicted immediately after they have been written out. Callers outside
buf_flush_page_cleaner() will pass evict=true, to retain the existing
behaviour.
buf_do_LRU_batch(): Add the parameter bool evict.
Return counts of evicted and flushed pages.
buf_flush_LRU(): Add the parameter bool evict.
Assume that the caller holds buf_pool.mutex and
will invoke buf_dblwr.flush_buffered_writes() afterwards.
buf_flush_list_holding_mutex(): A low-level variant of buf_flush_list()
whose caller must hold buf_pool.mutex and invoke
buf_dblwr.flush_buffered_writes() afterwards.
buf_flush_wait_batch_end_acquiring_mutex(): Remove. It is enough to have
buf_flush_wait_batch_end().
page_cleaner_flush_pages_recommendation(): Avoid some floating-point
arithmetics.
buf_flush_page(), buf_flush_check_neighbor(), buf_flush_check_neighbors(),
buf_flush_try_neighbors(): Rename the parameter "bool lru" to "bool evict".
buf_free_from_unzip_LRU_list_batch(): Remove the parameter.
Only actual page writes will contribute towards the limit.
buf_LRU_free_page(): Evict freed pages of temporary tables.
buf_pool.done_free: Broadcast whenever a block is freed
(and buf_pool.try_LRU_scan is set).
buf_pool_t::io_buf_t::reserve(): Retry indefinitely.
During the test encryption.innochecksum we easily run out of
these buffers for PAGE_COMPRESSED or ENCRYPTED pages.
Tested by Matthias Leich and Axel Schwenke
		
	
			
		
			
				
	
	
		
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			144 lines
		
	
	
	
		
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| /*****************************************************************************
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| 
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| Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
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| Copyright (c) 2014, 2021, MariaDB Corporation.
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| 
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| This program is free software; you can redistribute it and/or modify it under
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| the terms of the GNU General Public License as published by the Free Software
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| Foundation; version 2 of the License.
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| 
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| This program is distributed in the hope that it will be useful, but WITHOUT
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| ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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| FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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| 
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| You should have received a copy of the GNU General Public License along with
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| this program; if not, write to the Free Software Foundation, Inc.,
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| 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
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| 
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| *****************************************************************************/
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| 
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| /**************************************************//**
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| @file include/buf0flu.h
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| The database buffer pool flush algorithm
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| 
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| Created 11/5/1995 Heikki Tuuri
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| *******************************************************/
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| 
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| #ifndef buf0flu_h
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| #define buf0flu_h
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| 
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| #include "ut0byte.h"
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| #include "log0log.h"
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| #include "buf0types.h"
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| 
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| /** Number of pages flushed. Protected by buf_pool.mutex. */
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| extern ulint buf_flush_page_count;
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| /** Number of pages flushed via LRU. Protected by buf_pool.mutex.
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| Also included in buf_flush_page_count. */
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| extern ulint buf_lru_flush_page_count;
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| 
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| /** Flag indicating if the page_cleaner is in active state. */
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| extern bool buf_page_cleaner_is_active;
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| 
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| /** Remove all dirty pages belonging to a given tablespace when we are
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| deleting the data file of that tablespace.
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| The pages still remain a part of LRU and are evicted from
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| the list as they age towards the tail of the LRU.
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| @param id    tablespace identifier */
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| void buf_flush_remove_pages(ulint id);
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| 
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| /*******************************************************************//**
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| Relocates a buffer control block on the flush_list.
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| Note that it is assumed that the contents of bpage has already been
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| copied to dpage. */
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| ATTRIBUTE_COLD
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| void
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| buf_flush_relocate_on_flush_list(
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| /*=============================*/
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| 	buf_page_t*	bpage,	/*!< in/out: control block being moved */
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| 	buf_page_t*	dpage);	/*!< in/out: destination block */
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| 
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| /** Complete write of a file page from buf_pool.
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| @param request write request */
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| void buf_page_write_complete(const IORequest &request);
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| 
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| /** Assign the full crc32 checksum for non-compressed page.
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| @param[in,out]	page	page to be updated */
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| void buf_flush_assign_full_crc32_checksum(byte* page);
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| 
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| /** Initialize a page for writing to the tablespace.
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| @param[in]	block			buffer block; NULL if bypassing the buffer pool
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| @param[in,out]	page			page frame
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| @param[in,out]	page_zip_		compressed page, or NULL if uncompressed
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| @param[in]	use_full_checksum	whether tablespace uses full checksum */
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| void
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| buf_flush_init_for_writing(
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| 	const buf_block_t*	block,
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| 	byte*			page,
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| 	void*			page_zip_,
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| 	bool			use_full_checksum);
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| 
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| /** Try to flush dirty pages that belong to a given tablespace.
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| @param space       tablespace
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| @param n_flushed   number of pages written
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| @return whether the flush for some pages might not have been initiated */
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| bool buf_flush_list_space(fil_space_t *space, ulint *n_flushed= nullptr)
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|   MY_ATTRIBUTE((warn_unused_result));
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| 
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| /** Write out dirty blocks from buf_pool.LRU,
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| and move clean blocks to buf_pool.free.
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| The caller must invoke buf_dblwr.flush_buffered_writes()
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| after releasing buf_pool.mutex.
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| @param max_n    wished maximum mumber of blocks flushed
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| @param evict    whether to evict pages after flushing
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| @return evict ? number of processed pages : number of pages written
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| @retval 0 if a buf_pool.LRU batch is already running */
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| ulint buf_flush_LRU(ulint max_n, bool evict);
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| 
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| /** Wait until a flush batch ends.
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| @param lru    true=buf_pool.LRU; false=buf_pool.flush_list */
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| void buf_flush_wait_batch_end(bool lru);
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| /** Wait until all persistent pages are flushed up to a limit.
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| @param sync_lsn   buf_pool.get_oldest_modification(LSN_MAX) to wait for */
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| ATTRIBUTE_COLD void buf_flush_wait_flushed(lsn_t sync_lsn);
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| /** Initiate more eager page flushing if the log checkpoint age is too old.
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| @param lsn      buf_pool.get_oldest_modification(LSN_MAX) target
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| @param furious  true=furious flushing, false=limit to innodb_io_capacity */
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| ATTRIBUTE_COLD void buf_flush_ahead(lsn_t lsn, bool furious);
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| 
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| /********************************************************************//**
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| This function should be called at a mini-transaction commit, if a page was
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| modified in it. Puts the block to the list of modified blocks, if it not
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| already in it. */
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| UNIV_INLINE
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| void
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| buf_flush_note_modification(
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| /*========================*/
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| 	buf_block_t*	block,		/*!< in: block which is modified */
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| 	lsn_t		start_lsn,	/*!< in: start lsn of the first mtr in a
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| 					set of mtr's */
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| 	lsn_t		end_lsn);	/*!< in: end lsn of the last mtr in the
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| 					set of mtr's */
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| 
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| /** Initialize page_cleaner. */
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| ATTRIBUTE_COLD void buf_flush_page_cleaner_init();
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| 
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| /** Flush the buffer pool on shutdown. */
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| ATTRIBUTE_COLD void buf_flush_buffer_pool();
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| 
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| #ifdef UNIV_DEBUG
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| /** Validate the flush list. */
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| void buf_flush_validate();
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| #endif /* UNIV_DEBUG */
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| 
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| /** Synchronously flush dirty blocks during recv_sys_t::apply().
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| NOTE: The calling thread is not allowed to hold any buffer page latches! */
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| void buf_flush_sync_batch(lsn_t lsn);
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| 
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| /** Synchronously flush dirty blocks.
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| NOTE: The calling thread is not allowed to hold any buffer page latches! */
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| void buf_flush_sync();
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| 
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| #include "buf0flu.inl"
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| 
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| #endif
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