*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/buffer/buf_init.c,v 1.70 2004/12/31 22:00:49 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/buffer/buf_init.c,v 1.71 2005/02/03 23:29:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
* aborts, it should only unpin the buffers exactly the number of times it
* has pinned them, so that it will not blow away buffers of another
* backend.
- *
*/
block = BufferBlocks;
/*
- * link the buffers into a single linked list. This will become
- * the LIFO list of unused buffers returned by
- * StrategyGetBuffer().
+ * Initialize all the buffer headers.
*/
for (i = 0; i < NBuffers; block += BLCKSZ, buf++, i++)
{
Assert(ShmemIsValid((unsigned long) block));
+ /*
+ * The bufNext fields link together all totally-unused buffers.
+ * Subsequent management of this list is done by
+ * StrategyGetBuffer().
+ */
buf->bufNext = i + 1;
CLEAR_BUFFERTAG(buf->tag);
buf->wait_backend_id = 0;
}
- /* Correct last entry */
+ /* Correct last entry of linked list */
BufferDescriptors[NBuffers - 1].bufNext = -1;
LWLockRelease(BufMgrLock);
/*
* Convert shmem offsets into addresses as seen by this process. This
- * is just to speed up the BufferGetBlock() macro.
+ * is just to speed up the BufferGetBlock() macro. It is OK to do this
+ * without any lock since the data pointers never change.
*/
for (i = 0; i < NBuffers; i++)
BufferBlockPointers[i] = (Block) MAKE_PTR(BufferDescriptors[i].data);
/* size of data pages */
size += NBuffers * MAXALIGN(BLCKSZ);
- /* size of buffer hash table */
- size += hash_estimate_size(NBuffers * 2, sizeof(BufferLookupEnt));
-
- /* size of the shared replacement strategy control block */
- size += MAXALIGN(sizeof(BufferStrategyControl));
-
- /* size of the ARC directory blocks */
- size += MAXALIGN(NBuffers * 2 * sizeof(BufferStrategyCDB));
+ /* size of stuff controlled by freelist.c */
+ size += StrategyShmemSize();
return size;
}
/*-------------------------------------------------------------------------
*
* buf_table.c
- * routines for finding buffers in the buffer pool.
+ * routines for mapping BufferTags to buffer indexes.
*
- * NOTE: these days, what this table actually provides is a mapping from
- * BufferTags to CDB indexes, not directly to buffers. The function names
- * are thus slight misnomers.
+ * NOTE: this module is called only by freelist.c, and the "buffer IDs"
+ * it deals with are whatever freelist.c needs them to be; they may not be
+ * directly equivalent to Buffer numbers.
*
* Note: all routines in this file assume that the BufMgrLock is held
* by the caller, so no synchronization is needed.
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/buffer/buf_table.c,v 1.38 2004/12/31 22:00:49 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/buffer/buf_table.c,v 1.39 2005/02/03 23:29:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "storage/bufmgr.h"
+/* entry for buffer lookup hashtable */
+typedef struct
+{
+ BufferTag key; /* Tag of a disk page */
+ int id; /* Associated buffer ID */
+} BufferLookupEnt;
+
static HTAB *SharedBufHash;
+/*
+ * Estimate space needed for mapping hashtable
+ * size is the desired hash table size (possibly more than NBuffers)
+ */
+int
+BufTableShmemSize(int size)
+{
+ return hash_estimate_size(size, sizeof(BufferLookupEnt));
+}
+
/*
* Initialize shmem hash table for mapping buffers
- * size is the desired hash table size (2*NBuffers for ARC algorithm)
+ * size is the desired hash table size (possibly more than NBuffers)
*/
void
InitBufTable(int size)
/*
* BufTableLookup
- * Lookup the given BufferTag; return CDB index, or -1 if not found
+ * Lookup the given BufferTag; return buffer ID, or -1 if not found
*/
int
BufTableLookup(BufferTag *tagPtr)
/*
* BufTableInsert
- * Insert a hashtable entry for given tag and CDB index
+ * Insert a hashtable entry for given tag and buffer ID
*/
void
-BufTableInsert(BufferTag *tagPtr, int cdb_id)
+BufTableInsert(BufferTag *tagPtr, int buf_id)
{
BufferLookupEnt *result;
bool found;
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of shared memory")));
- if (found) /* found something else in the table? */
+ if (found) /* found something already in the table? */
elog(ERROR, "shared buffer hash table corrupted");
- result->id = cdb_id;
+ result->id = buf_id;
}
/*
* BufTableDelete
- * Delete the hashtable entry for given tag
+ * Delete the hashtable entry for given tag (which must exist)
*/
void
BufTableDelete(BufferTag *tagPtr)
* 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.
*
*
*
* 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 1.50 2005/02/03 23:29:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#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;
}
+/*
+ * 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.
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.75 2004/12/31 22:03:42 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.76 2005/02/03 23:29:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "storage/backendid.h"
#include "storage/buf.h"
-#include "storage/lmgr.h"
#include "storage/lwlock.h"
+#include "storage/shmem.h"
+#include "utils/rel.h"
/*
* Buffer tag identifies which disk block the buffer contains.
*
* Note: the BufferTag data must be sufficient to determine where to write the
- * block, even during a "blind write" with no relcache entry. It's possible
- * that the backend flushing the buffer doesn't even believe the relation is
- * visible yet (its xact may have started before the xact that created the
- * rel). The storage manager must be able to cope anyway.
+ * block, without reference to pg_class or pg_tablespace entries. It's
+ * possible that the backend flushing the buffer doesn't even believe the
+ * relation is visible yet (its xact may have started before the xact that
+ * created the rel). The storage manager must be able to cope anyway.
*
* Note: if there's any pad bytes in the struct, INIT_BUFFERTAG will have
* to be fixed to zero them, since this struct is used as a hash key.
#define BufferDescriptorGetBuffer(bdesc) ((bdesc)->buf_id + 1)
-/* entry for buffer lookup hashtable */
-typedef struct
-{
- BufferTag key; /* Tag of a disk page */
- int id; /* CDB id of associated CDB */
-} BufferLookupEnt;
-
-/*
- * 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;
+/* in bufmgr.c */
+extern BufferDesc *BufferDescriptors;
+/* in localbuf.c */
+extern BufferDesc *LocalBufferDescriptors;
/* counters in buf_init.c */
extern long int ReadBufferCount;
/*
- * Bufmgr Interface:
+ * Internal routines: only called by bufmgr
*/
-/* Internal routines: only called by bufmgr */
-
/* freelist.c */
extern BufferDesc *StrategyBufferLookup(BufferTag *tagPtr, bool recheck,
int *cdb_found_index);
extern void StrategyHintVacuum(bool vacuum_active);
extern int StrategyDirtyBufferList(BufferDesc **buffers, BufferTag *buftags,
int max_buffers);
+extern int StrategyShmemSize(void);
extern void StrategyInitialize(bool init);
/* buf_table.c */
+extern int BufTableShmemSize(int size);
extern void InitBufTable(int size);
extern int BufTableLookup(BufferTag *tagPtr);
-extern void BufTableInsert(BufferTag *tagPtr, int cdb_id);
+extern void BufTableInsert(BufferTag *tagPtr, int buf_id);
extern void BufTableDelete(BufferTag *tagPtr);
-/* bufmgr.c */
-extern BufferDesc *BufferDescriptors;
-
/* localbuf.c */
-extern BufferDesc *LocalBufferDescriptors;
-
extern BufferDesc *LocalBufferAlloc(Relation reln, BlockNumber blockNum,
bool *foundPtr);
extern void WriteLocalBuffer(Buffer buffer, bool release);
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