>From f7bf4813eeee7d5c3c4268e0fb6231ca6996d9fe Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Thu, 30 Oct 2014 13:24:20 +0100 Subject: [PATCH 1/2] Faster PageIsVerified() for the all zeroes case. --- src/backend/storage/page/bufpage.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/page/bufpage.c b/src/backend/storage/page/bufpage.c index 6351a9b..c175ed0 100644 --- a/src/backend/storage/page/bufpage.c +++ b/src/backend/storage/page/bufpage.c @@ -81,7 +81,7 @@ bool PageIsVerified(Page page, BlockNumber blkno) { PageHeader p = (PageHeader) page; - char *pagebytes; + size_t *pagebytes; int i; bool checksum_failure = false; bool header_sane = false; @@ -118,10 +118,17 @@ PageIsVerified(Page page, BlockNumber blkno) return true; } - /* Check all-zeroes case */ + /* + * Check all-zeroes case. Luckily BLCKSZ is guaranteed to always be a + * multiple of size_t - and it's much faster compare memory using the + * processor's native word size. + */ + StaticAssertStmt(BLCKSZ == (BLCKSZ / sizeof(size_t)) * sizeof(size_t), + "BLCKSZ has to be a multiple of sizeof(size_t)"); + all_zeroes = true; - pagebytes = (char *) page; - for (i = 0; i < BLCKSZ; i++) + pagebytes = (size_t *) page; + for (i = 0; i < (BLCKSZ / sizeof(size_t)); i++) { if (pagebytes[i] != 0) { -- 2.0.0.rc2.4.g1dc51c6.dirty