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Allow background writing to be shut down by setting limit values to zero.

2004年10月17日 22:01:51 +0000 (22:01 +0000)

This does not disable the bgwriter process: it still has to wake up often
enough to collect fsync requests from backends in a timely fashion. But
it responds to the recent gripe about not being able to prevent the disk
from being spun up constantly.

doc/src/sgml/runtime.sgml patch | blob | blame | history

src/backend/storage/buffer/bufmgr.c patch | blob | blame | history

src/backend/utils/misc/guc.c patch | blob | blame | history

src/backend/utils/misc/postgresql.conf.sample patch | blob | blame | history

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml

index f82fbc877def92e787b15238d52547f65d4bb9f0..b4a84616f54ac08e3a191174f116dad70a7419f9 100644 (file)

--- a/doc/src/sgml/runtime.sgml

+++ b/doc/src/sgml/runtime.sgml

@@ -1,5 +1,5 @@

<!--

-$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.288 2004年10月15日 16:50:29 momjian Exp $

+$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.289 2004年10月17日 22:01:49 tgl Exp $

-->

@@ -1305,7 +1305,9 @@ SET ENABLE_SEQSCAN TO OFF;

<varname>bgwriter_maxpages</varname> reduce the extra I/O load

caused by the background writer, but leave more work to be done

at checkpoint time. To reduce load spikes at checkpoints,

- increase the values.

+ increase the values. To disable background writing entirely,

+ set <varname>bgwriter_percent</varname> and/or

+ <varname>bgwriter_maxpages</varname> to zero.

</para>

</sect3>

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c

index b9d8fc3ad53d06746d5f7071732f949422660771..c96c635d0a6c67b2bac466b9f46c159ac1d571aa 100644 (file)

--- a/src/backend/storage/buffer/bufmgr.c

+++ b/src/backend/storage/buffer/bufmgr.c

@@ -8,7 +8,7 @@

* IDENTIFICATION

- * $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.180 2004年10月16日 18:57:23 tgl Exp $

+ * $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.181 2004年10月17日 22:01:50 tgl Exp $

*-------------------------------------------------------------------------

@@ -671,8 +671,10 @@ UnpinBuffer(BufferDesc *buf, bool fixOwner)

* This is called at checkpoint time to write out all dirty shared buffers,

* and by the background writer process to write out some of the dirty blocks.

- * percent/maxpages should be zero in the former case, and nonzero limit

- * values in the latter.

+ * percent/maxpages should be -1 in the former case, and limit values (>= 0)

+ * in the latter.

+ *

+ * Returns the number of buffers written.

int

BufferSync(int percent, int maxpages)

@@ -682,6 +684,10 @@ BufferSync(int percent, int maxpages)

int num_buffer_dirty;

int i;

+ /* If either limit is zero then we are disabled from doing anything... */

+ if (percent == 0 || maxpages == 0)

+ return 0;

* Get a list of all currently dirty buffers and how many there are.

* We do not flush buffers that get dirtied after we started. They

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c

index 5f3ac94bd50a0fcc3602984a6deb8638b09aec79..5b5a2a309f648cd5b55307383326400a65982280 100644 (file)

--- a/src/backend/utils/misc/guc.c

+++ b/src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@

* Written by Peter Eisentraut <peter_e@gmx.net>.

* IDENTIFICATION

- * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.244 2004年10月16日 19:08:38 tgl Exp $

+ * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.245 2004年10月17日 22:01:51 tgl Exp $

*--------------------------------------------------------------------

@@ -1248,7 +1248,7 @@ static struct config_int ConfigureNamesInt[] =

NULL

&BgWriterDelay,

- 200, 10, 5000, NULL, NULL

+ 200, 10, 10000, NULL, NULL

{

@@ -1257,7 +1257,7 @@ static struct config_int ConfigureNamesInt[] =

NULL

&BgWriterPercent,

- 1, 1, 100, NULL, NULL

+ 1, 0, 100, NULL, NULL

{

@@ -1266,7 +1266,7 @@ static struct config_int ConfigureNamesInt[] =

NULL

&BgWriterMaxPages,

- 100, 1, 1000, NULL, NULL

+ 100, 0, 1000, NULL, NULL

{

diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample

index 59004a73c058d1f89801b9fb674a117b74fd60ff..3aed76a411ee03c153390345a56d69562370f696 100644 (file)

--- a/src/backend/utils/misc/postgresql.conf.sample

+++ b/src/backend/utils/misc/postgresql.conf.sample

@@ -98,9 +98,9 @@

# - Background writer -

-#bgwriter_delay = 200 # 10-5000 milliseconds

-#bgwriter_percent = 1 # 1-100% of dirty buffers

-#bgwriter_maxpages = 100 # 1-1000 buffers max at once

+#bgwriter_delay = 200 # 10-10000 milliseconds between rounds

+#bgwriter_percent = 1 # 0-100% of dirty buffers in each round

+#bgwriter_maxpages = 100 # 0-1000 buffers max per round

#---------------------------------------------------------------------------

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