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Add some instrumentation to the bgwriter, through the stats collector.

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New view pg_stat_bgwriter, and the functions required to build it.
This commit is contained in:
Magnus Hagander
2007-03-30 18:34:56 +00:00
parent f9ce21f94c
commit 335feca441
10 changed files with 349 additions and 12 deletions
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12
src/backend/catalog/system_views.sql
View File

@@ -3,7 +3,7 @@
*
* Copyright (c) 1996-2007, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/backend/catalog/system_views.sql,v 1.36 2007/03/16 17:57:36 mha Exp $
* $PostgreSQL: pgsql/src/backend/catalog/system_views.sql,v 1.37 2007/03/30 18:34:55 mha Exp $
*/
CREATE VIEW pg_roles AS
@@ -364,3 +364,13 @@ CREATE VIEW pg_stat_database AS
pg_stat_get_db_tuples_updated(D.oid) AS tup_updated,
pg_stat_get_db_tuples_deleted(D.oid) AS tup_deleted
FROM pg_database D;
CREATE VIEW pg_stat_bgwriter AS
SELECT
pg_stat_get_bgwriter_timed_checkpoints() AS checkpoints_timed,
pg_stat_get_bgwriter_requested_checkpoints() AS checkpoints_req,
pg_stat_get_bgwriter_buf_written_checkpoints() AS buffers_checkpoint,
pg_stat_get_bgwriter_buf_written_lru() AS buffers_lru,
pg_stat_get_bgwriter_buf_written_all() AS buffers_all,
pg_stat_get_bgwriter_maxwritten_lru() AS maxwritten_lru,
pg_stat_get_bgwriter_maxwritten_all() AS maxwritten_all;

25
src/backend/postmaster/bgwriter.c
View File

@@ -37,7 +37,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.36 2007/01/17 16:25:01 tgl Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.37 2007/03/30 18:34:55 mha Exp $
*
*-------------------------------------------------------------------------
*/
@@ -50,6 +50,7 @@
#include "access/xlog_internal.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/bgwriter.h"
#include "storage/fd.h"
#include "storage/freespace.h"
@@ -124,6 +125,13 @@ typedef struct
static BgWriterShmemStruct *BgWriterShmem;
/*
* BgWriter statistics counters.
* Stored directly in a stats message structure so it can be sent
* without needing to copy things around.
*/
PgStat_MsgBgWriter BgWriterStats;
/*
* GUC parameters
*/
@@ -242,6 +250,11 @@ BackgroundWriterMain(void)
ALLOCSET_DEFAULT_MAXSIZE);
MemoryContextSwitchTo(bgwriter_context);
/*
* Initialize statistics counters to zero
*/
memset(&BgWriterStats, 0, sizeof(BgWriterStats));
/*
* If an exception is encountered, processing resumes here.
*
@@ -354,6 +367,7 @@ BackgroundWriterMain(void)
checkpoint_requested = false;
do_checkpoint = true;
force_checkpoint = true;
BgWriterStats.m_requested_checkpoints++;
}
if (shutdown_requested)
{
@@ -376,7 +390,11 @@ BackgroundWriterMain(void)
now = time(NULL);
elapsed_secs = now - last_checkpoint_time;
if (elapsed_secs >= CheckPointTimeout)
{
do_checkpoint = true;
if (!force_checkpoint)
BgWriterStats.m_timed_checkpoints++;
}
/*
* Do a checkpoint if requested, otherwise do one cycle of
@@ -473,6 +491,11 @@ BackgroundWriterMain(void)
}
}
/*
* Send off activity statistics to the stats collector
*/
pgstat_send_bgwriter();
/*
* Nap for the configured time, or sleep for 10 seconds if there is no
* bgwriter activity configured.

111
src/backend/postmaster/pgstat.c
View File

@@ -13,7 +13,7 @@
*
* Copyright (c) 2001-2007, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.151 2007/03/28 22:17:12 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.152 2007/03/30 18:34:55 mha Exp $
* ----------
*/
#include "postgres.h"
@@ -135,6 +135,18 @@ static HTAB *pgStatDBHash = NULL;
static PgBackendStatus *localBackendStatusTable = NULL;
static int localNumBackends = 0;
/*
* BgWriter global statistics counters, from bgwriter.c
*/
extern PgStat_MsgBgWriter BgWriterStats;
/*
* Cluster wide statistics, kept in the stats collector.
* Contains statistics that are not collected per database
* or per table.
*/
static PgStat_GlobalStats globalStats;
static volatile bool need_exit = false;
static volatile bool need_statwrite = false;
@@ -171,6 +183,7 @@ static void pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int len);
static void pgstat_recv_autovac(PgStat_MsgAutovacStart *msg, int len);
static void pgstat_recv_vacuum(PgStat_MsgVacuum *msg, int len);
static void pgstat_recv_analyze(PgStat_MsgAnalyze *msg, int len);
static void pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len);
/* ------------------------------------------------------------
@@ -1288,6 +1301,22 @@ pgstat_fetch_stat_numbackends(void)
return localNumBackends;
}
/*
* ---------
* pgstat_fetch_global() -
*
* Support function for the SQL-callable pgstat* functions. Returns
* a pointer to the global statistics struct.
* ---------
*/
PgStat_GlobalStats *
pgstat_fetch_global(void)
{
backend_read_statsfile();
return &globalStats;
}
/* ------------------------------------------------------------
* Functions for management of the shared-memory PgBackendStatus array
@@ -1646,6 +1675,42 @@ pgstat_send(void *msg, int len)
#endif
}
/* ----------
* pgstat_send_bgwriter() -
*
* Send bgwriter statistics to the collector
* ----------
*/
void
pgstat_send_bgwriter(void)
{
/*
* This function can be called even if nothing at all has happened.
* In this case, avoid sending a completely empty message to
* the stats collector.
*/
if (BgWriterStats.m_timed_checkpoints == 0 &&
BgWriterStats.m_requested_checkpoints == 0 &&
BgWriterStats.m_buf_written_checkpoints == 0 &&
BgWriterStats.m_buf_written_lru == 0 &&
BgWriterStats.m_buf_written_all == 0 &&
BgWriterStats.m_maxwritten_lru == 0 &&
BgWriterStats.m_maxwritten_all == 0)
return;
/*
* Prepare and send the message
*/
pgstat_setheader(&BgWriterStats.m_hdr, PGSTAT_MTYPE_BGWRITER);
pgstat_send(&BgWriterStats, sizeof(BgWriterStats));
/*
* Clear out the bgwriter statistics buffer, so it can be
* re-used.
*/
memset(&BgWriterStats, 0, sizeof(BgWriterStats));
}
/* ----------
* PgstatCollectorMain() -
@@ -1892,6 +1957,10 @@ PgstatCollectorMain(int argc, char *argv[])
pgstat_recv_analyze((PgStat_MsgAnalyze *) &msg, len);
break;
case PGSTAT_MTYPE_BGWRITER:
pgstat_recv_bgwriter((PgStat_MsgBgWriter *) &msg, len);
break;
default:
break;
}
@@ -2030,6 +2099,11 @@ pgstat_write_statsfile(void)
format_id = PGSTAT_FILE_FORMAT_ID;
fwrite(&format_id, sizeof(format_id), 1, fpout);
/*
* Write global stats struct
*/
fwrite(&globalStats, sizeof(globalStats), 1, fpout);
/*
* Walk through the database table.
*/
@@ -2132,6 +2206,12 @@ pgstat_read_statsfile(Oid onlydb)
dbhash = hash_create("Databases hash", PGSTAT_DB_HASH_SIZE, &hash_ctl,
HASH_ELEM | HASH_FUNCTION | HASH_CONTEXT);
/*
* Clear out global statistics so they start from zero in case we can't
* load an existing statsfile.
*/
memset(&globalStats, 0, sizeof(globalStats));
/*
* Try to open the status file. If it doesn't exist, the backends simply
* return zero for anything and the collector simply starts from scratch
@@ -2151,6 +2231,16 @@ pgstat_read_statsfile(Oid onlydb)
goto done;
}
/*
* Read global stats struct
*/
if (fread(&globalStats, 1, sizeof(globalStats), fpin) != sizeof(globalStats))
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted pgstat.stat file")));
goto done;
}
/*
* We found an existing collector stats file. Read it and put all the
* hashtable entries into place.
@@ -2656,3 +2746,22 @@ pgstat_recv_analyze(PgStat_MsgAnalyze *msg, int len)
tabentry->n_dead_tuples = msg->m_dead_tuples;
tabentry->last_anl_tuples = msg->m_live_tuples + msg->m_dead_tuples;
}
/* ----------
* pgstat_recv_bgwriter() -
*
* Process a BGWRITER message.
* ----------
*/
static void
pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len)
{
globalStats.timed_checkpoints += msg->m_timed_checkpoints;
globalStats.requested_checkpoints += msg->m_requested_checkpoints;
globalStats.buf_written_checkpoints += msg->m_buf_written_checkpoints;
globalStats.buf_written_lru += msg->m_buf_written_lru;
globalStats.buf_written_all += msg->m_buf_written_all;
globalStats.maxwritten_lru += msg->m_maxwritten_lru;
globalStats.maxwritten_all += msg->m_maxwritten_all;
}

18
src/backend/storage/buffer/bufmgr.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.215 2007/02/01 19:10:27 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.216 2007/03/30 18:34:55 mha Exp $
*
*-------------------------------------------------------------------------
*/
@@ -80,6 +80,12 @@ static bool IsForInput;
/* local state for LockBufferForCleanup */
static volatile BufferDesc *PinCountWaitBuf = NULL;
/*
* Global statistics for the bgwriter. The contents of this variable
* only makes sense in the bgwriter process.
*/
extern PgStat_MsgBgWriter BgWriterStats;
static bool PinBuffer(volatile BufferDesc *buf);
static void PinBuffer_Locked(volatile BufferDesc *buf);
@@ -964,6 +970,8 @@ BufferSync(void)
{
if (SyncOneBuffer(buf_id, false))
{
BgWriterStats.m_buf_written_checkpoints++;
/*
* If in bgwriter, absorb pending fsync requests after each
* WRITES_PER_ABSORB write operations, to prevent overflow of the
@@ -1027,9 +1035,13 @@ BgBufferSync(void)
if (SyncOneBuffer(buf_id1, false))
{
if (++num_written >= bgwriter_all_maxpages)
{
BgWriterStats.m_maxwritten_all++;
break;
}
}
}
BgWriterStats.m_buf_written_all += num_written;
}
/*
@@ -1048,11 +1060,15 @@ BgBufferSync(void)
if (SyncOneBuffer(buf_id2, true))
{
if (++num_written >= bgwriter_lru_maxpages)
{
BgWriterStats.m_maxwritten_lru++;
break;
}
}
if (++buf_id2 >= NBuffers)
buf_id2 = 0;
}
BgWriterStats.m_buf_written_lru += num_written;
}
}

54
src/backend/utils/adt/pgstatfuncs.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.40 2007/03/16 17:57:36 mha Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.41 2007/03/30 18:34:55 mha Exp $
*
*-------------------------------------------------------------------------
*/
@@ -61,9 +61,19 @@ extern Datum pg_stat_get_db_tuples_inserted(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_updated(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_deleted(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_timed_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_requested_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_lru(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_all(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_maxwritten_lru(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_maxwritten_all(PG_FUNCTION_ARGS);
extern Datum pg_stat_clear_snapshot(PG_FUNCTION_ARGS);
extern Datum pg_stat_reset(PG_FUNCTION_ARGS);
/* Global bgwriter statistics, from bgwriter.c */
extern PgStat_MsgBgWriter bgwriterStats;
Datum
pg_stat_get_numscans(PG_FUNCTION_ARGS)
@@ -756,6 +766,48 @@ pg_stat_get_db_tuples_deleted(PG_FUNCTION_ARGS)
PG_RETURN_INT64(result);
}
Datum
pg_stat_get_bgwriter_timed_checkpoints(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->timed_checkpoints);
}
Datum
pg_stat_get_bgwriter_requested_checkpoints(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->requested_checkpoints);
}
Datum
pg_stat_get_bgwriter_buf_written_checkpoints(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->buf_written_checkpoints);
}
Datum
pg_stat_get_bgwriter_buf_written_lru(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->buf_written_lru);
}
Datum
pg_stat_get_bgwriter_buf_written_all(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->buf_written_all);
}
Datum
pg_stat_get_bgwriter_maxwritten_lru(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->maxwritten_lru);
}
Datum
pg_stat_get_bgwriter_maxwritten_all(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->maxwritten_all);
}
/* Discard the active statistics snapshot */
Datum