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Increase the number of buffer mapping partitions to 128.

Testing by Amit Kapila, Andres Freund, and myself, with and withoutother patches that also aim to improve scalability, seems to indicatethat this change is a significant win over the current value and oversmaller values such as 64. It's not clear how high we can push thisvalue before it starts to have negative side-effects elsewhere, butgoing this far looks OK.

1 parent9528726 commit3acc10cCopy full SHA for 3acc10c

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2 files changed

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lines changed

src
- backend/storage/lmgr
  - lwlock.c
- include/storage
  - lwlock.h

2 files changed

-5

lines changed

`‎src/backend/storage/lmgr/lwlock.c`

Lines changed: 4 additions & 4 deletions

Original file line number	Diff line number	Diff line change
`@@ -73,11 +73,11 @@ static LWLockTranche MainLWLockTranche;`
`73`	`73`
`74`	`74`	`/*`
`75`	`75`	`* We use this structure to keep track of locked LWLocks for release`
`76`		`- * during error recovery.The maximum size couldbedetermined atruntime`
`77`		`- *if necessary, but it seems unlikely that more than a few locks could`
`78`		`- *ever be held simultaneously.`
	`76`	`+ * during error recovery.Normally, only a few willbeheld atonce, but`
	`77`	`+ *occasionally the number can be much higher; for example, the pg_buffercache`
	`78`	`+ *extension locks all buffer partitions simultaneously.`
`79`	`79`	`*/`
`80`		`-#defineMAX_SIMUL_LWLOCKS100`
	`80`	`+#defineMAX_SIMUL_LWLOCKS200`
`81`	`81`
`82`	`82`	`staticintnum_held_lwlocks=0;`
`83`	`83`	`staticLWLock*held_lwlocks[MAX_SIMUL_LWLOCKS];`

`‎src/include/storage/lwlock.h`

Lines changed: 1 addition & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -136,7 +136,7 @@ extern PGDLLIMPORT LWLockPadded *MainLWLockArray;`
`136`	`136`	`*/`
`137`	`137`
`138`	`138`	`/* Number of partitions of the shared buffer mapping hashtable */`
`139`		`-#defineNUM_BUFFER_PARTITIONS16`
	`139`	`+#defineNUM_BUFFER_PARTITIONS128`
`140`	`140`
`141`	`141`	`/* Number of partitions the shared lock tables are divided into */`
`142`	`142`	`#defineLOG2_NUM_LOCK_PARTITIONS 4`

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Commit3acc10c

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2 files changed

2 files changed

`‎src/backend/storage/lmgr/lwlock.c`

`‎src/include/storage/lwlock.h`

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