From 6c992bfc815c837568e3001ba0f01e6e90d9dc61 Mon Sep 17 00:00:00 2001 From: David Christensen Date: Fri, 29 Sep 2023 15:03:00 -0400 Subject: [PATCH v2 3/9] Use fastdiv code in visibility map Adjust the code that calculates our heap block offsets based to be based on PageUsableSpace instead of compile-time constants. Use the fastdiv code to support this. --- src/backend/access/heap/visibilitymap.c | 92 ++++++++++++++++++------- 1 file changed, 67 insertions(+), 25 deletions(-) diff --git a/src/backend/access/heap/visibilitymap.c b/src/backend/access/heap/visibilitymap.c index 0bbd95be8f..206aef33d1 100644 --- a/src/backend/access/heap/visibilitymap.c +++ b/src/backend/access/heap/visibilitymap.c @@ -105,18 +105,24 @@ * extra headers, so the whole page minus the standard page header is * used for the bitmap. */ -#define MAPSIZE (PageUsableSpace) /* Number of heap blocks we can represent in one byte */ #define HEAPBLOCKS_PER_BYTE (BITS_PER_BYTE / BITS_PER_HEAPBLOCK) +/* Init routine for our fastmath */ +#define MAPBLOCK_INIT if (unlikely(!mapblock_size)) \ + { \ + mapblock_size = PageUsableSpace; \ + mapblock_inv = pg_fastinverse(mapblock_size); \ + } + /* Number of heap blocks we can represent in one visibility map page. */ -#define HEAPBLOCKS_PER_PAGE (MAPSIZE * HEAPBLOCKS_PER_BYTE) +#define HEAPBLOCKS_PER_PAGE (mapblock_size << BITS_PER_HEAPBLOCK) /* Mapping from heap block number to the right bit in the visibility map */ -#define HEAPBLK_TO_MAPBLOCK(x) ((x) / HEAPBLOCKS_PER_PAGE) -#define HEAPBLK_TO_MAPBYTE(x) (((x) % HEAPBLOCKS_PER_PAGE) / HEAPBLOCKS_PER_BYTE) -#define HEAPBLK_TO_OFFSET(x) (((x) % HEAPBLOCKS_PER_BYTE) * BITS_PER_HEAPBLOCK) +#define HEAPBLK_TO_MAPBLOCK(x) (pg_fastdiv((x),mapblock_size,mapblock_inv)) +#define HEAPBLK_TO_MAPBYTE(x) (pg_fastmod((x),mapblock_size,mapblock_inv) >> 2) /* always 4 blocks per byte */ +#define HEAPBLK_TO_OFFSET(x) (((x) & 0x3) << 1) /* always 2 bits per entry */ /* Masks for counting subsets of bits in the visibility map. */ #define VISIBLE_MASK64 UINT64CONST(0x5555555555555555) /* The lower bit of each @@ -128,6 +134,9 @@ static Buffer vm_readbuf(Relation rel, BlockNumber blkno, bool extend); static Buffer vm_extend(Relation rel, BlockNumber vm_nblocks); +/* storage for the fast div/mod inverse */ +static uint64 mapblock_inv = 0; +static uint32 mapblock_size = 0; /* * visibilitymap_clear - clear specified bits for one page in visibility map @@ -139,13 +148,20 @@ static Buffer vm_extend(Relation rel, BlockNumber vm_nblocks); bool visibilitymap_clear(Relation rel, BlockNumber heapBlk, Buffer vmbuf, uint8 flags) { - BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); - int mapByte = HEAPBLK_TO_MAPBYTE(heapBlk); - int mapOffset = HEAPBLK_TO_OFFSET(heapBlk); - uint8 mask = flags << mapOffset; + BlockNumber mapBlock; + int mapByte; + int mapOffset; + uint8 mask; char *map; bool cleared = false; + MAPBLOCK_INIT; + + mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); + mapByte = HEAPBLK_TO_MAPBYTE(heapBlk); + mapOffset = HEAPBLK_TO_OFFSET(heapBlk); + mask = flags << mapOffset; + /* Must never clear all_visible bit while leaving all_frozen bit set */ Assert(flags & VISIBILITYMAP_VALID_BITS); Assert(flags != VISIBILITYMAP_ALL_VISIBLE); @@ -192,7 +208,11 @@ visibilitymap_clear(Relation rel, BlockNumber heapBlk, Buffer vmbuf, uint8 flags void visibilitymap_pin(Relation rel, BlockNumber heapBlk, Buffer *vmbuf) { - BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); + BlockNumber mapBlock; + + MAPBLOCK_INIT; + + mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); /* Reuse the old pinned buffer if possible */ if (BufferIsValid(*vmbuf)) @@ -216,7 +236,11 @@ visibilitymap_pin(Relation rel, BlockNumber heapBlk, Buffer *vmbuf) bool visibilitymap_pin_ok(BlockNumber heapBlk, Buffer vmbuf) { - BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); + BlockNumber mapBlock; + + MAPBLOCK_INIT; + + mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); return BufferIsValid(vmbuf) && BufferGetBlockNumber(vmbuf) == mapBlock; } @@ -247,12 +271,18 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf, XLogRecPtr recptr, Buffer vmBuf, TransactionId cutoff_xid, uint8 flags) { - BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); - uint32 mapByte = HEAPBLK_TO_MAPBYTE(heapBlk); - uint8 mapOffset = HEAPBLK_TO_OFFSET(heapBlk); + BlockNumber mapBlock; + uint32 mapByte; + uint8 mapOffset; Page page; uint8 *map; + MAPBLOCK_INIT; + + mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); + mapByte = HEAPBLK_TO_MAPBYTE(heapBlk); + mapOffset = HEAPBLK_TO_OFFSET(heapBlk); + #ifdef TRACE_VISIBILITYMAP elog(DEBUG1, "vm_set %s %d", RelationGetRelationName(rel), heapBlk); #endif @@ -337,12 +367,18 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf, uint8 visibilitymap_get_status(Relation rel, BlockNumber heapBlk, Buffer *vmbuf) { - BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); - uint32 mapByte = HEAPBLK_TO_MAPBYTE(heapBlk); - uint8 mapOffset = HEAPBLK_TO_OFFSET(heapBlk); + BlockNumber mapBlock; + uint32 mapByte; + uint8 mapOffset; char *map; uint8 result; + MAPBLOCK_INIT; + + mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); + mapByte = HEAPBLK_TO_MAPBYTE(heapBlk); + mapOffset = HEAPBLK_TO_OFFSET(heapBlk); + #ifdef TRACE_VISIBILITYMAP elog(DEBUG1, "vm_get_status %s %d", RelationGetRelationName(rel), heapBlk); #endif @@ -414,16 +450,16 @@ visibilitymap_count(Relation rel, BlockNumber *all_visible, BlockNumber *all_fro */ map = (uint64 *) PageGetContents(BufferGetPage(mapBuffer)); - StaticAssertStmt(MAPSIZE % sizeof(uint64) == 0, - "unsupported MAPSIZE"); + Assert(mapblock_size % sizeof(uint64) == 0); + if (all_frozen == NULL) { - for (i = 0; i < MAPSIZE / sizeof(uint64); i++) + for (i = 0; i < mapblock_size / sizeof(uint64); i++) nvisible += pg_popcount64(map[i] & VISIBLE_MASK64); } else { - for (i = 0; i < MAPSIZE / sizeof(uint64); i++) + for (i = 0; i < mapblock_size / sizeof(uint64); i++) { nvisible += pg_popcount64(map[i] & VISIBLE_MASK64); nfrozen += pg_popcount64(map[i] & FROZEN_MASK64); @@ -455,9 +491,15 @@ visibilitymap_prepare_truncate(Relation rel, BlockNumber nheapblocks) BlockNumber newnblocks; /* last remaining block, byte, and bit */ - BlockNumber truncBlock = HEAPBLK_TO_MAPBLOCK(nheapblocks); - uint32 truncByte = HEAPBLK_TO_MAPBYTE(nheapblocks); - uint8 truncOffset = HEAPBLK_TO_OFFSET(nheapblocks); + BlockNumber truncBlock; + uint32 truncByte; + uint8 truncOffset; + + MAPBLOCK_INIT; + + truncBlock = HEAPBLK_TO_MAPBLOCK(nheapblocks); + truncByte = HEAPBLK_TO_MAPBYTE(nheapblocks); + truncOffset = HEAPBLK_TO_OFFSET(nheapblocks); #ifdef TRACE_VISIBILITYMAP elog(DEBUG1, "vm_truncate %s %d", RelationGetRelationName(rel), nheapblocks); @@ -501,7 +543,7 @@ visibilitymap_prepare_truncate(Relation rel, BlockNumber nheapblocks) START_CRIT_SECTION(); /* Clear out the unwanted bytes. */ - MemSet(&map[truncByte + 1], 0, MAPSIZE - (truncByte + 1)); + MemSet(&map[truncByte + 1], 0, mapblock_size - (truncByte + 1)); /*---- * Mask out the unwanted bits of the last remaining byte. -- 2.40.1