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Avoid XLogFlush for clean buffers in BufferSync.

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This commit is contained in:
Vadim B. Mikheev 2000-12-22 20:04:43 +00:00
parent 387d43113c
commit 369aace5f3
1 changed files with 21 additions and 10 deletions
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31
src/backend/storage/buffer/bufmgr.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.98 2000/11/30 19:03:25 vadim Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.99 2000/12/22 20:04:43 vadim Exp $
*
*-------------------------------------------------------------------------
*/
@ -723,6 +723,7 @@ BufferSync()
RelFileNode rnode;
XLogRecPtr recptr;
Relation reln = NULL;
bool dirty = false;
for (i = 0, bufHdr = BufferDescriptors; i < NBuffers; i++, bufHdr++)
{
@ -745,6 +746,7 @@ BufferSync()
buffer = BufferDescriptorGetBuffer(bufHdr);
rnode = bufHdr->tag.rnode;
dirty = bufHdr->flags & BM_DIRTY;
SpinRelease(BufMgrLock);
@ -758,6 +760,17 @@ BufferSync()
*/
LockBuffer(buffer, BUFFER_LOCK_SHARE);
if (!dirty && !(bufHdr->cntxDirty))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
SpinAcquire(BufMgrLock);
UnpinBuffer(bufHdr);
SpinRelease(BufMgrLock);
if (reln != (Relation) NULL)
RelationDecrementReferenceCount(reln);
continue;
}
/*
* Force XLOG flush for buffer' LSN
*/
@ -766,9 +779,8 @@ BufferSync()
/*
* Now it's safe to write buffer to disk
* (if needed at all -:))
* (if no one else already)
*/
SpinAcquire(BufMgrLock);
if (bufHdr->flags & BM_IO_IN_PROGRESS)
WaitIO(bufHdr, BufMgrLock);
@ -824,20 +836,19 @@ BufferSync()
*/
if (!(bufHdr->flags & BM_JUST_DIRTIED))
bufHdr->flags &= ~BM_DIRTY;
UnpinBuffer(bufHdr);
SpinRelease(BufMgrLock);
}
else
{
UnpinBuffer(bufHdr);
SpinRelease(BufMgrLock);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
UnpinBuffer(bufHdr);
SpinRelease(BufMgrLock);
}
/* drop refcnt obtained by RelationNodeCacheGetRelation */
if (reln != (Relation) NULL)
{
RelationDecrementReferenceCount(reln);
reln = NULL;
}
}
}