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Replace the BufMgrLock with separate locks on the lookup hashtable and

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the freelist, plus per-buffer spinlocks that protect access to individual
shared buffer headers.  This requires abandoning a global freelist (since
the freelist is a global contention point), which shoots down ARC and 2Q
as well as plain LRU management.  Adopt a clock sweep algorithm instead.
Preliminary results show substantial improvement in multi-backend situations.
This commit is contained in:
Tom Lane
2005-03-04 20:21:07 +00:00
parent 5592a6cf46
commit 5d5087363d
18 changed files with 1410 additions and 1932 deletions
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9
src/backend/utils/resowner/resowner.c
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@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/resowner/resowner.c,v 1.9 2004/12/31 22:02:50 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/utils/resowner/resowner.c,v 1.10 2005/03/04 20:21:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -200,12 +200,7 @@ ResourceOwnerReleaseInternal(ResourceOwner owner,
* that would indicate failure to clean up the executor correctly ---
* so issue warnings. In the abort case, just clean up quietly.
*
* XXX this is fairly inefficient due to multiple BufMgrLock
* grabs if there are lots of buffers to be released, but we
* don't expect many (indeed none in the success case) so it's
* probably not worth optimizing.
*
* We are however careful to release back-to-front, so as to
* We are careful to do the releasing back-to-front, so as to
* avoid O(N^2) behavior in ResourceOwnerForgetBuffer().
*/
while (owner->nbuffers > 0)