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Use pg_memory_is_all_zeros() in PageIsVerifiedExtended()

Relying on pg_memory_is_all_zeros(), which would apply SIMD instructionswhen dealing with an aligned page, is proving to be at least three timesfaster than the original size_t-based comparisons when checking if aBLCKSZ page is full of zeros. Note that PageIsVerifiedExtended() iscalled each time a page is read from disk, and making it faster is agood thing.Author: Bertrand DrouvotDiscussion:https://postgr.es/m/CAApHDvq7P-JgFhgtxUPqhavG-qSDVUhyWaEX9M8_MNorFEijZA@mail.gmail.com

1 parent5be1dab commit03a42c9Copy full SHA for 03a42c9

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src/backend/storage/page
- bufpage.c

1 file changed

-12

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`‎src/backend/storage/page/bufpage.c‎`

Lines changed: 1 addition & 12 deletions

Original file line number	Diff line number	Diff line change
`@@ -89,10 +89,8 @@ PageIsVerifiedExtended(Page page, BlockNumber blkno, int flags)`
`89`	`89`	`{`
`90`	`90`	`PageHeaderp= (PageHeader)page;`
`91`	`91`	`size_t*pagebytes;`
`92`		`-inti;`
`93`	`92`	`boolchecksum_failure= false;`
`94`	`93`	`boolheader_sane= false;`
`95`		`-boolall_zeroes= false;`
`96`	`94`	`uint16checksum=0;`
`97`	`95`
`98`	`96`	`/*`
`@@ -126,18 +124,9 @@ PageIsVerifiedExtended(Page page, BlockNumber blkno, int flags)`
`126`	`124`	`}`
`127`	`125`
`128`	`126`	`/* Check all-zeroes case */`
`129`		`-all_zeroes= true;`
`130`	`127`	`pagebytes= (size_t*)page;`
`131`		`-for (i=0;i< (BLCKSZ /sizeof(size_t));i++)`
`132`		`-{`
`133`		`-if (pagebytes[i]!=0)`
`134`		`-{`
`135`		`-all_zeroes= false;`
`136`		`-break;`
`137`		`-}`
`138`		`-}`
`139`	`128`
`140`		`-if (all_zeroes)`
	`129`	`+if (pg_memory_is_all_zeros(pagebytes,BLCKSZ))`
`141`	`130`	`return true;`
`142`	`131`
`143`	`132`	`/*`

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Commit03a42c9

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`‎src/backend/storage/page/bufpage.c‎`

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