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Implement "distributed" checkpoints in which the checkpoint I/O is spread

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over a fairly long period of time, rather than being spat out in a burst.
This happens only for background checkpoints carried out by the bgwriter;
other cases, such as a shutdown checkpoint, are still done at full speed.

Remove the "all buffers" scan in the bgwriter, and associated stats
infrastructure, since this seems no longer very useful when the checkpoint
itself is properly throttled.

Original patch by Itagaki Takahiro, reworked by Heikki Linnakangas,
and some minor API editorialization by me.
This commit is contained in:
Tom Lane
2007-06-28 00:02:40 +00:00
parent b09c248bdd
commit 867e2c91a0
22 changed files with 760 additions and 463 deletions
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28
src/backend/utils/adt/pgstatfuncs.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.42 2007/05/17 23:31:49 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.43 2007/06/28 00:02:39 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -64,10 +64,8 @@ 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_get_bgwriter_buf_written_clean(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_maxwritten_clean(PG_FUNCTION_ARGS);
extern Datum pg_stat_clear_snapshot(PG_FUNCTION_ARGS);
extern Datum pg_stat_reset(PG_FUNCTION_ARGS);
@@ -787,27 +785,15 @@ pg_stat_get_bgwriter_buf_written_checkpoints(PG_FUNCTION_ARGS)
}
Datum
pg_stat_get_bgwriter_buf_written_lru(PG_FUNCTION_ARGS)
pg_stat_get_bgwriter_buf_written_clean(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->buf_written_lru);
PG_RETURN_INT64(pgstat_fetch_global()->buf_written_clean);
}
Datum
pg_stat_get_bgwriter_buf_written_all(PG_FUNCTION_ARGS)
pg_stat_get_bgwriter_maxwritten_clean(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);
PG_RETURN_INT64(pgstat_fetch_global()->maxwritten_clean);
}

29
src/backend/utils/misc/guc.c
View File

@@ -10,7 +10,7 @@
* Written by Peter Eisentraut <peter_e@gmx.net>.
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.402 2007/06/21 22:59:12 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.403 2007/06/28 00:02:39 tgl Exp $
*
*--------------------------------------------------------------------
*/
@@ -1573,15 +1573,6 @@ static struct config_int ConfigureNamesInt[] =
5, 0, 1000, NULL, NULL
},
{
{"bgwriter_all_maxpages", PGC_SIGHUP, RESOURCES,
gettext_noop("Background writer maximum number of all pages to flush per round."),
NULL
},
&bgwriter_all_maxpages,
5, 0, 1000, NULL, NULL
},
{
{"log_rotation_age", PGC_SIGHUP, LOGGING_WHERE,
gettext_noop("Automatic log file rotation will occur after N minutes."),
@@ -1834,15 +1825,6 @@ static struct config_real ConfigureNamesReal[] =
1.0, 0.0, 100.0, NULL, NULL
},
{
{"bgwriter_all_percent", PGC_SIGHUP, RESOURCES,
gettext_noop("Background writer percentage of all buffers to flush per round."),
NULL
},
&bgwriter_all_percent,
0.333, 0.0, 100.0, NULL, NULL
},
{
{"seed", PGC_USERSET, UNGROUPED,
gettext_noop("Sets the seed for random-number generation."),
@@ -1870,6 +1852,15 @@ static struct config_real ConfigureNamesReal[] =
0.1, 0.0, 100.0, NULL, NULL
},
{
{"checkpoint_completion_target", PGC_SIGHUP, WAL_CHECKPOINTS,
gettext_noop("Time spent flushing dirty buffers during checkpoint, as fraction of checkpoint interval."),
NULL
},
&CheckPointCompletionTarget,
0.5, 0.0, 1.0, NULL, NULL
},
/* End-of-list marker */
{
{NULL, 0, 0, NULL, NULL}, NULL, 0.0, 0.0, 0.0, NULL, NULL

3
src/backend/utils/misc/postgresql.conf.sample
View File

@@ -140,8 +140,6 @@
#bgwriter_delay = 200ms # 10-10000ms between rounds
#bgwriter_lru_percent = 1.0 # 0-100% of LRU buffers scanned/round
#bgwriter_lru_maxpages = 5 # 0-1000 buffers max written/round
#bgwriter_all_percent = 0.333 # 0-100% of all buffers scanned/round
#bgwriter_all_maxpages = 5 # 0-1000 buffers max written/round
#---------------------------------------------------------------------------
@@ -168,6 +166,7 @@
#checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
#checkpoint_timeout = 5min # range 30s-1h
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_warning = 30s # 0 is off
# - Archiving -