diff options
Diffstat (limited to 'src/backend/storage/buffer/freelist.c')
| -rw-r--r-- | src/backend/storage/buffer/freelist.c | 74 |
1 files changed, 73 insertions, 1 deletions
diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index eb38fcf21af..fe1a2eab519 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -3,6 +3,11 @@ * freelist.c * routines for manipulating the buffer pool's replacement strategy. * + * The name "freelist.c" is now a bit of a misnomer, since this module + * controls not only the list of free buffers per se, but the entire + * mechanism for looking up existing shared buffers and the strategy + * for choosing replacement victims when needed. + * * Note: all routines in this file assume that the BufMgrLock is held * by the caller, so no synchronization is needed. * @@ -12,7 +17,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.49 2004/12/31 22:00:49 pgsql Exp $ + * $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.49.4.1 2005/02/03 23:30:04 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -25,6 +30,51 @@ #include "storage/bufmgr.h" +/* + * Definitions for the buffer replacement strategy + */ +#define STRAT_LIST_UNUSED (-1) +#define STRAT_LIST_B1 0 +#define STRAT_LIST_T1 1 +#define STRAT_LIST_T2 2 +#define STRAT_LIST_B2 3 +#define STRAT_NUM_LISTS 4 + +/* + * The Cache Directory Block (CDB) of the Adaptive Replacement Cache (ARC) + */ +typedef struct +{ + int prev; /* list links */ + int next; + short list; /* ID of list it is currently in */ + bool t1_vacuum; /* t => present only because of VACUUM */ + TransactionId t1_xid; /* the xid this entry went onto T1 */ + BufferTag buf_tag; /* page identifier */ + int buf_id; /* currently assigned data buffer, or -1 */ +} BufferStrategyCDB; + +/* + * The shared ARC control information. + */ +typedef struct +{ + int target_T1_size; /* What T1 size are we aiming for */ + int listUnusedCDB; /* All unused StrategyCDB */ + int listHead[STRAT_NUM_LISTS]; /* ARC lists B1, T1, T2 + * and B2 */ + int listTail[STRAT_NUM_LISTS]; + int listSize[STRAT_NUM_LISTS]; + Buffer listFreeBuffers; /* List of unused buffers */ + + long num_lookup; /* Some hit statistics */ + long num_hit[STRAT_NUM_LISTS]; + time_t stat_report; + + /* Array of CDB's starts here */ + BufferStrategyCDB cdb[1]; /* VARIABLE SIZE ARRAY */ +} BufferStrategyControl; + /* GUC variable: time in seconds between statistics reports */ int DebugSharedBuffers = 0; @@ -813,6 +863,28 @@ StrategyDirtyBufferList(BufferDesc **buffers, BufferTag *buftags, /* + * StrategyShmemSize + * + * estimate the size of shared memory used by the freelist-related structures. + */ +int +StrategyShmemSize(void) +{ + int size = 0; + + /* size of CDB lookup hash table */ + size += BufTableShmemSize(NBuffers * 2); + + /* size of the shared replacement strategy control block */ + size += MAXALIGN(sizeof(BufferStrategyControl)); + + /* size of the ARC directory blocks */ + size += MAXALIGN(NBuffers * 2 * sizeof(BufferStrategyCDB)); + + return size; +} + +/* * StrategyInitialize -- initialize the buffer cache replacement * strategy. * |