From cb2fa6f0245b28a1d3f83ac901eb0d8698f22dd3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?C=C3=A9dric=20Villemain?= Date: Wed, 3 Jan 2024 20:16:37 +0100 Subject: [PATCH 3/3] Allow pg_prewarm to use new smgrreadv This commit replaces smgrread with smgrreadv (with range). I also defined a PREWARM_READ_RANGE, 8 by default, which is the number of buffers to read in one call. I just discovered pg_readv so I hope the initialization I wrote is correct. It's not really sure there is a huge win because all blocks are sequential and readv should merge them but not use vectorization (if I understood correctly). --- contrib/pg_prewarm/pg_prewarm.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/contrib/pg_prewarm/pg_prewarm.c b/contrib/pg_prewarm/pg_prewarm.c index aea07927db..e11694d707 100644 --- a/contrib/pg_prewarm/pg_prewarm.c +++ b/contrib/pg_prewarm/pg_prewarm.c @@ -26,6 +26,7 @@ #include "utils/rel.h" #define PREWARM_PREFETCH_RANGE RELSEG_SIZE +#define PREWARM_READ_RANGE 8 PG_MODULE_MAGIC; @@ -38,7 +39,7 @@ typedef enum PREWARM_BUFFER, } PrewarmType; -static PGIOAlignedBlock blockbuffer; +static PGIOAlignedBlock blockbuffers[PREWARM_READ_RANGE]; /* * pg_prewarm(regclass, mode text, fork text, @@ -187,11 +188,19 @@ pg_prewarm(PG_FUNCTION_ARGS) * buffers. This is more portable than prefetch mode (it works * everywhere) and is synchronous. */ - for (block = first_block; block <= last_block; ++block) + char *buffers[PREWARM_READ_RANGE]; + for (int i=0; i < PREWARM_READ_RANGE; i++) + buffers[i] = blockbuffers[i].data; + for (block = first_block; block <= last_block; + block += PREWARM_READ_RANGE) { + int seek = Min(PREWARM_READ_RANGE, (last_block - block + 1)); + CHECK_FOR_INTERRUPTS(); - smgrread(RelationGetSmgr(rel), forkNumber, block, blockbuffer.data); - ++blocks_done; + + smgrreadv(RelationGetSmgr(rel), forkNumber, block, (void *) buffers, + seek); + blocks_done += seek; } } else if (ptype == PREWARM_BUFFER) -- 2.39.2