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Added GUC variable bgwriter_flush_method controlling the action

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done by the background writer between writing dirty blocks and
napping.

    none (default)   no action
	sync             bgwriter calls smgrsync() causing a sync(2)

A global sync() is only good on dedicated database servers, so
more flush methods should be added in the future.

Jan
This commit is contained in:
Jan Wieck
2004-01-24 20:00:46 +00:00
parent 610d33c194
commit d77b63b17c
4 changed files with 68 additions and 5 deletions
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51
src/backend/storage/buffer/bufmgr.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.152 2004/01/09 21:08:49 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.153 2004/01/24 20:00:45 wieck Exp $
*
*-------------------------------------------------------------------------
*/
@ -55,6 +55,7 @@
#include "storage/proc.h"
#include "storage/smgr.h"
#include "utils/relcache.h"
#include "utils/guc.h"
#include "pgstat.h"
@ -65,9 +66,23 @@
/* GUC variable */
bool zero_damaged_pages = false;
#define BGWRITER_FLUSH_NONE 0
#define BGWRITER_FLUSH_NONE_STR "none"
#define BGWRITER_FLUSH_SYNC 1
#define BGWRITER_FLUSH_SYNC_STR "sync"
#define BGWRITER_FLUSH_DEFAULT BGWRITER_FLUSH_NONE
#define BGWRITER_FLUSH_DEFAULT_STR BGWRITER_FLUSH_NONE_STR
int BgWriterDelay = 200;
int BgWriterPercent = 1;
int BgWriterMaxpages = 100;
int BgWriterFlushMethod = BGWRITER_FLUSH_NONE;
char *BgWriterFlushMethod_str = NULL;
const char BgWriterFlushMethod_default[] = BGWRITER_FLUSH_DEFAULT_STR;
const char *BgWriterAssignSyncMethod(const char *method,
bool doit, GucSource source);
static void WaitIO(BufferDesc *buf);
static void StartBufferIO(BufferDesc *buf, bool forInput);
@ -1026,6 +1041,19 @@ BufferBackgroundWriter(void)
if (InterruptPending)
return;
/*
* Perform the configured buffer flush method
*/
switch (BgWriterFlushMethod)
{
case BGWRITER_FLUSH_NONE:
break;
case BGWRITER_FLUSH_SYNC:
smgrsync();
break;
}
/*
* Nap for the configured time or sleep for 10 seconds if
* there was nothing to do at all.
@ -1037,6 +1065,27 @@ BufferBackgroundWriter(void)
}
}
const char *
BgWriterAssignSyncMethod(const char *method, bool doit, GucSource source)
{
int new_flush_method;
if (strcasecmp(method, BGWRITER_FLUSH_NONE_STR) == 0)
new_flush_method = BGWRITER_FLUSH_NONE;
else
if (strcasecmp(method, BGWRITER_FLUSH_SYNC_STR) == 0)
new_flush_method = BGWRITER_FLUSH_SYNC;
else
return NULL;
if (!doit)
return method;
BgWriterFlushMethod = new_flush_method;
return method;
}
/*
* Do whatever is needed to prepare for commit at the bufmgr and smgr levels
*/