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author Thomas Munro <tmunro@postgresql.org>

2023年12月16日 03:14:47 +0000 (16:14 +1300)

committer Thomas Munro <tmunro@postgresql.org>

2023年12月16日 04:51:21 +0000 (17:51 +1300)

Previously smgrprefetch() could issue POSIX_FADV_WILLNEED advice for a
single block at a time. Add an nblocks argument so that we can do the
same for a range of blocks. This usually produces a single system call,
but might need to loop if it crosses a segment boundary. Initially it
is only called with nblocks == 1, but proposed patches will make wider
calls.

Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> (earlier version)
Discussion: https://postgr.es/m/CA+hUKGJkOiOCa+mag4BF+zHo7qo=o9CFheB8=g6uT5TUm2gkvA@mail.gmail.com

src/backend/storage/buffer/bufmgr.c patch | blob | blame | history

src/backend/storage/buffer/localbuf.c patch | blob | blame | history

src/backend/storage/smgr/md.c patch | blob | blame | history

src/backend/storage/smgr/smgr.c patch | blob | blame | history

src/include/storage/md.h patch | blob | blame | history

src/include/storage/smgr.h patch | blob | blame | history

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c

index f7c67d504cd038a9607de02625536a02488258db..de8b5edbfbfbeb8f5b9304cd79ba646e940b33cd 100644 (file)

--- a/src/backend/storage/buffer/bufmgr.c

+++ b/src/backend/storage/buffer/bufmgr.c

@@ -569,7 +569,7 @@ PrefetchSharedBuffer(SMgrRelation smgr_reln,

* recovery if the relation file doesn't exist.

if ((io_direct_flags & IO_DIRECT_DATA) == 0 &&

- smgrprefetch(smgr_reln, forkNum, blockNum))

+ smgrprefetch(smgr_reln, forkNum, blockNum, 1))

{

result.initiated_io = true;

}

diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c

index aebcf146b451feb1c21f86bda14270a89d3c4c54..c75ed184e04434be04b61329c05a968be14ab124 100644 (file)

--- a/src/backend/storage/buffer/localbuf.c

+++ b/src/backend/storage/buffer/localbuf.c

@@ -94,7 +94,7 @@ PrefetchLocalBuffer(SMgrRelation smgr, ForkNumber forkNum,

#ifdef USE_PREFETCH

/* Not in buffers, so initiate prefetch */

if ((io_direct_flags & IO_DIRECT_DATA) == 0 &&

- smgrprefetch(smgr, forkNum, blockNum))

+ smgrprefetch(smgr, forkNum, blockNum, 1))

{

result.initiated_io = true;

}

diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c

index fdecbad17095743c1b0e178d3a6dbd98aa6817fd..091993ea45b6e72596c96a00ed796b30abcc45a1 100644 (file)

--- a/src/backend/storage/smgr/md.c

+++ b/src/backend/storage/smgr/md.c

@@ -710,27 +710,44 @@ mdclose(SMgrRelation reln, ForkNumber forknum)

}

- * mdprefetch() -- Initiate asynchronous read of the specified block of a relation

+ * mdprefetch() -- Initiate asynchronous read of the specified blocks of a relation

bool

-mdprefetch(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum)

+mdprefetch(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,

+ int nblocks)

{

#ifdef USE_PREFETCH

- off_t seekpos;

- MdfdVec *v;

Assert((io_direct_flags & IO_DIRECT_DATA) == 0);

- v = _mdfd_getseg(reln, forknum, blocknum, false,

- InRecovery ? EXTENSION_RETURN_NULL : EXTENSION_FAIL);

- if (v == NULL)

+ if ((uint64) blocknum + nblocks > (uint64) MaxBlockNumber + 1)

return false;

- seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));

+ while (nblocks > 0)

+ {

+ off_t seekpos;

+ MdfdVec *v;

+ int nblocks_this_segment;

- Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);

+ v = _mdfd_getseg(reln, forknum, blocknum, false,

+ InRecovery ? EXTENSION_RETURN_NULL : EXTENSION_FAIL);

+ if (v == NULL)

+ return false;

+ seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));

- (void) FilePrefetch(v->mdfd_vfd, seekpos, BLCKSZ, WAIT_EVENT_DATA_FILE_PREFETCH);

+ Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);

+ nblocks_this_segment =

+ Min(nblocks,

+ RELSEG_SIZE - (blocknum % ((BlockNumber) RELSEG_SIZE)));

+ (void) FilePrefetch(v->mdfd_vfd, seekpos, BLCKSZ * nblocks_this_segment,

+ WAIT_EVENT_DATA_FILE_PREFETCH);

+ blocknum += nblocks_this_segment;

+ nblocks -= nblocks_this_segment;

+ }

#endif /* USE_PREFETCH */

return true;

diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c

index 4c552649336ee92157c34b629de7bba4557b6447..003a55a592c29b9e85cb5e4a364dad6f7a292b6e 100644 (file)

--- a/src/backend/storage/smgr/smgr.c

+++ b/src/backend/storage/smgr/smgr.c

@@ -54,7 +54,7 @@ typedef struct f_smgr

void (*smgr_zeroextend) (SMgrRelation reln, ForkNumber forknum,

BlockNumber blocknum, int nblocks, bool skipFsync);

bool (*smgr_prefetch) (SMgrRelation reln, ForkNumber forknum,

- BlockNumber blocknum);

+ BlockNumber blocknum, int nblocks);

void (*smgr_read) (SMgrRelation reln, ForkNumber forknum,

BlockNumber blocknum, void *buffer);

void (*smgr_write) (SMgrRelation reln, ForkNumber forknum,

@@ -547,9 +547,10 @@ smgrzeroextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,

* record).

bool

-smgrprefetch(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum)

+smgrprefetch(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,

+ int nblocks)

{

- return smgrsw[reln->smgr_which].smgr_prefetch(reln, forknum, blocknum);

+ return smgrsw[reln->smgr_which].smgr_prefetch(reln, forknum, blocknum, nblocks);

}

diff --git a/src/include/storage/md.h b/src/include/storage/md.h

index 941879ee6a8fda631cea27f07f8a40601fce501f..091784c171e353b268e487ad73431527fd8970df 100644 (file)

--- a/src/include/storage/md.h

+++ b/src/include/storage/md.h

@@ -31,7 +31,7 @@ extern void mdextend(SMgrRelation reln, ForkNumber forknum,

extern void mdzeroextend(SMgrRelation reln, ForkNumber forknum,

BlockNumber blocknum, int nblocks, bool skipFsync);

extern bool mdprefetch(SMgrRelation reln, ForkNumber forknum,

- BlockNumber blocknum);

+ BlockNumber blocknum, int nblocks);

extern void mdread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,

void *buffer);

extern void mdwrite(SMgrRelation reln, ForkNumber forknum,

diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h

index a9a179aabacc488b7bd5d1e9de88c05df3891c3a..da7e7c5a2e6a97b28b4610a699ee86a6f7b75ad8 100644 (file)

--- a/src/include/storage/smgr.h

+++ b/src/include/storage/smgr.h

@@ -95,7 +95,7 @@ extern void smgrextend(SMgrRelation reln, ForkNumber forknum,

extern void smgrzeroextend(SMgrRelation reln, ForkNumber forknum,

BlockNumber blocknum, int nblocks, bool skipFsync);

extern bool smgrprefetch(SMgrRelation reln, ForkNumber forknum,

- BlockNumber blocknum);

+ BlockNumber blocknum, int nblocks);

extern void smgrread(SMgrRelation reln, ForkNumber forknum,

BlockNumber blocknum, void *buffer);

extern void smgrwrite(SMgrRelation reln, ForkNumber forknum,

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