InnoDB Plugin  1.0
Data Structures | Macros | Functions | Variables
buf0lru.h File Reference
#include "univ.i"
#include "ut0byte.h"
#include "buf0types.h"
#include "buf0lru.ic"
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Data Structures

struct  buf_LRU_stat_t
 Statistics for selecting the LRU list for eviction. More...


#define BUF_LRU_OLD_MIN_LEN   512 /* 8 megabytes of 16k pages */
#define buf_LRU_stat_inc_io()
#define buf_LRU_stat_inc_unzip()   buf_LRU_stat_cur.unzip++


UNIV_INTERN ibool buf_LRU_buf_pool_running_out (void)
UNIV_INTERN void buf_LRU_flush_or_remove_pages (ulint id, buf_remove_t buf_remove, const trx_t *trx)
UNIV_INTERN void buf_LRU_insert_zip_clean (buf_page_t *bpage)
UNIV_INTERN bool buf_LRU_free_page (buf_page_t *bpage, bool zip))
UNIV_INTERN ibool buf_LRU_scan_and_free_block (buf_pool_t *buf_pool, ibool scan_all))
UNIV_INTERN buf_block_tbuf_LRU_get_free_only (buf_pool_t *buf_pool)
UNIV_INTERN buf_block_tbuf_LRU_get_free_block (buf_pool_t *buf_pool))
UNIV_INTERN ibool buf_LRU_evict_from_unzip_LRU (buf_pool_t *buf_pool)
UNIV_INTERN void buf_LRU_block_free_non_file_page (buf_block_t *block)
UNIV_INTERN void buf_LRU_add_block (buf_page_t *bpage, ibool old)
UNIV_INTERN void buf_unzip_LRU_add_block (buf_block_t *block, ibool old)
UNIV_INTERN void buf_LRU_make_block_young (buf_page_t *bpage)
UNIV_INTERN void buf_LRU_make_block_old (buf_page_t *bpage)
UNIV_INTERN ulint buf_LRU_old_ratio_update (uint old_pct, ibool adjust)
UNIV_INTERN void buf_LRU_stat_update (void)
UNIV_INTERN void buf_LRU_free_one_page (buf_page_t *bpage))
UNIV_INTERN ibool buf_LRU_validate (void)
UNIV_INTERN void buf_LRU_print (void)


buf_LRU_stat_t buf_LRU_stat_cur
buf_LRU_stat_t buf_LRU_stat_sum

Heuristics for detecting index scan @{

#define BUF_LRU_OLD_RATIO_DIV   1024
#define BUF_LRU_OLD_RATIO_MIN   51
uint buf_LRU_old_threshold_ms

Detailed Description

The database buffer pool LRU replacement algorithm

Created 11/5/1995 Heikki Tuuri

Macro Definition Documentation

#define BUF_LRU_OLD_MIN_LEN   512 /* 8 megabytes of 16k pages */

Minimum LRU list length for which the LRU_old pointer is defined

#define BUF_LRU_OLD_RATIO_DIV   1024

The denominator of buf_pool->LRU_old_ratio.

Maximum value of buf_pool->LRU_old_ratio.
See Also
#define BUF_LRU_OLD_RATIO_MIN   51
Minimum value of buf_pool->LRU_old_ratio.
See Also
buf_pool->LRU_old_ratio_update The minimum must exceed (BUF_LRU_OLD_TOLERANCE + 5) * BUF_LRU_OLD_RATIO_DIV / BUF_LRU_OLD_MIN_LEN.
#define buf_LRU_stat_inc_io ( )

Increments the I/O counter in buf_LRU_stat_cur.

#define buf_LRU_stat_inc_unzip ( )    buf_LRU_stat_cur.unzip++

Increments the page_zip_decompress() counter in buf_LRU_stat_cur.

Function Documentation

UNIV_INTERN void buf_LRU_add_block ( buf_page_t bpage,
ibool  old 

Adds a block to the LRU list. Please make sure that the zip_size is already set into the page zip when invoking the function, so that we can get correct zip_size from the buffer page when adding a block into LRU in: TRUE if should be put to the old blocks in the LRU list, else put to the start; if the LRU list is very short, added to the start regardless of this parameter

bpagein: control block
UNIV_INTERN void buf_LRU_block_free_non_file_page ( buf_block_t block)

Puts a block back to the free list. in: block, must not contain a file page

UNIV_INTERN ibool buf_LRU_buf_pool_running_out ( void  )

Returns TRUE if less than 25 % of the buffer pool is available. This can be used in heuristics to prevent huge transactions eating up the whole buffer pool for their locks.

TRUE if less than 25 % of buffer pool left
UNIV_INTERN ibool buf_LRU_evict_from_unzip_LRU ( buf_pool_t buf_pool)

Determines if the unzip_LRU list should be used for evicting a victim instead of the general LRU list.

TRUE if should use unzip_LRU
UNIV_INTERN void buf_LRU_flush_or_remove_pages ( ulint  id,
buf_remove_t  buf_remove,
const trx_t trx 

Flushes all dirty pages or removes all pages belonging to a given tablespace. A PROBLEM: if readahead is being started, what guarantees that it will not try to read in pages after this operation has completed? to check if the operation must be interrupted

idin: space id
buf_removein: remove or flush strategy
UNIV_INTERN void buf_LRU_free_one_page ( buf_page_t bpage)

Remove one page from LRU list and put it to free list

bpagein/out: block, must contain a file page and be in a state where it can be freed; there may or may not be a hash index to the page
UNIV_INTERN bool buf_LRU_free_page ( buf_page_t bpage,
bool  zip 

Try to free a block. If bpage is a descriptor of a compressed-only page, the descriptor object will be freed as well.

NOTE: If this function returns true, it will temporarily release buf_pool->mutex. Furthermore, the page frame will no longer be accessible via bpage.

The caller must hold buf_pool->mutex and must not hold any buf_page_get_mutex() when calling this function.

true if freed, false otherwise.
bpagein: block to be freed
zipin: true if should remove also the compressed page of an uncompressed page
UNIV_INTERN buf_block_t* buf_LRU_get_free_block ( buf_pool_t buf_pool)

Returns a free block from the buf_pool. The block is taken off the free list. If it is empty, blocks are moved from the end of the LRU list to the free list. This function is called from a user thread when it needs a clean block to read in a page. Note that we only ever get a block from the free list. Even when we flush a page or find a page in LRU scan we put it to free list to be used. iteration 0: get a block from free list, success:done if there is an LRU flush batch in progress: wait for batch to end: retry free list if buf_pool->try_LRU_scan is set scan LRU up to srv_LRU_scan_depth to find a clean block the above will put the block on free list success:retry the free list flush one dirty page from tail of LRU to disk the above will put the block on free list success: retry the free list iteration 1: same as iteration 0 except: scan whole LRU list scan LRU list even if buf_pool->try_LRU_scan is not set iteration > 1: same as iteration 1 but sleep 100ms

the free control block, in state BUF_BLOCK_READY_FOR_USE
buf_poolin/out: buffer pool instance
UNIV_INTERN buf_block_t* buf_LRU_get_free_only ( buf_pool_t buf_pool)

Returns a free block from the buf_pool. The block is taken off the free list. If it is empty, returns NULL.

a free control block, or NULL if the buf_block->free list is empty buffer pool instance
UNIV_INTERN void buf_LRU_insert_zip_clean ( buf_page_t bpage)

Insert a compressed block into buf_pool->zip_clean in the LRU order. in: pointer to the block in question

UNIV_INTERN void buf_LRU_make_block_old ( buf_page_t bpage)

Moves a block to the end of the LRU list. in: control block

UNIV_INTERN void buf_LRU_make_block_young ( buf_page_t bpage)

Moves a block to the start of the LRU list. in: control block

UNIV_INTERN ulint buf_LRU_old_ratio_update ( uint  old_pct,
ibool  adjust 

Updates buf_pool->LRU_old_ratio.

updated old_pct in: TRUE=adjust the LRU list; FALSE=just assign buf_pool->LRU_old_ratio during the initialization of InnoDB
old_pctin: Reserve this percentage of the buffer pool for "old" blocks.
UNIV_INTERN void buf_LRU_print ( void  )

Prints the LRU list.

UNIV_INTERN ibool buf_LRU_scan_and_free_block ( buf_pool_t buf_pool,
ibool  scan_all 

Try to free a replaceable block.

TRUE if found and freed
buf_poolin: buffer pool instance
scan_allin: scan whole LRU list if TRUE, otherwise scan only 'old' blocks.
UNIV_INTERN void buf_LRU_stat_update ( void  )

Update the historical stats that we are collecting for LRU eviction policy at the end of each interval.

UNIV_INTERN ibool buf_LRU_validate ( void  )

Validates the LRU list.

UNIV_INTERN void buf_unzip_LRU_add_block ( buf_block_t block,
ibool  old 

Adds a block to the LRU list of decompressed zip pages. in: TRUE if should be put to the end of the list, else put to the start

blockin: control block

Variable Documentation

uint buf_LRU_old_threshold_ms
Move blocks to "new" LRU list only if the first access was at

least this many milliseconds ago. Not protected by any mutex or latch.

buf_LRU_stat_t buf_LRU_stat_cur
Current operation counters.  Not protected by any mutex.

Cleared by buf_LRU_stat_update().

buf_LRU_stat_t buf_LRU_stat_sum
Running sum of past values of buf_LRU_stat_cur.

Updated by buf_LRU_stat_update(). Protected by buf_pool->mutex.