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Commitb485ad7

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Provide multi-block smgrprefetch().
Previously smgrprefetch() could issue POSIX_FADV_WILLNEED advice for asingle block at a time. Add an nblocks argument so that we can do thesame for a range of blocks. This usually produces a single system call,but might need to loop if it crosses a segment boundary. Initially itis only called with nblocks == 1, but proposed patches will make widercalls.Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> (earlier version)Discussion:https://postgr.es/m/CA+hUKGJkOiOCa+mag4BF+zHo7qo=o9CFheB8=g6uT5TUm2gkvA@mail.gmail.com
1 parent59bd34c commitb485ad7

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6 files changed

+35
-17
lines changed

6 files changed

+35
-17
lines changed

‎src/backend/storage/buffer/bufmgr.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -569,7 +569,7 @@ PrefetchSharedBuffer(SMgrRelation smgr_reln,
569569
* recovery if the relation file doesn't exist.
570570
*/
571571
if ((io_direct_flags&IO_DIRECT_DATA)==0&&
572-
smgrprefetch(smgr_reln,forkNum,blockNum))
572+
smgrprefetch(smgr_reln,forkNum,blockNum,1))
573573
{
574574
result.initiated_io= true;
575575
}

‎src/backend/storage/buffer/localbuf.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -94,7 +94,7 @@ PrefetchLocalBuffer(SMgrRelation smgr, ForkNumber forkNum,
9494
#ifdefUSE_PREFETCH
9595
/* Not in buffers, so initiate prefetch */
9696
if ((io_direct_flags&IO_DIRECT_DATA)==0&&
97-
smgrprefetch(smgr,forkNum,blockNum))
97+
smgrprefetch(smgr,forkNum,blockNum,1))
9898
{
9999
result.initiated_io= true;
100100
}

‎src/backend/storage/smgr/md.c

Lines changed: 27 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -710,27 +710,44 @@ mdclose(SMgrRelation reln, ForkNumber forknum)
710710
}
711711

712712
/*
713-
* mdprefetch() -- Initiate asynchronous read of the specifiedblock of a relation
713+
* mdprefetch() -- Initiate asynchronous read of the specifiedblocks of a relation
714714
*/
715715
bool
716-
mdprefetch(SMgrRelationreln,ForkNumberforknum,BlockNumberblocknum)
716+
mdprefetch(SMgrRelationreln,ForkNumberforknum,BlockNumberblocknum,
717+
intnblocks)
717718
{
718719
#ifdefUSE_PREFETCH
719-
off_tseekpos;
720-
MdfdVec*v;
721720

722721
Assert((io_direct_flags&IO_DIRECT_DATA)==0);
723722

724-
v=_mdfd_getseg(reln,forknum,blocknum, false,
725-
InRecovery ?EXTENSION_RETURN_NULL :EXTENSION_FAIL);
726-
if (v==NULL)
723+
if ((uint64)blocknum+nblocks> (uint64)MaxBlockNumber+1)
727724
return false;
728725

729-
seekpos= (off_t)BLCKSZ* (blocknum % ((BlockNumber)RELSEG_SIZE));
726+
while (nblocks>0)
727+
{
728+
off_tseekpos;
729+
MdfdVec*v;
730+
intnblocks_this_segment;
730731

731-
Assert(seekpos< (off_t)BLCKSZ*RELSEG_SIZE);
732+
v=_mdfd_getseg(reln,forknum,blocknum, false,
733+
InRecovery ?EXTENSION_RETURN_NULL :EXTENSION_FAIL);
734+
if (v==NULL)
735+
return false;
736+
737+
seekpos= (off_t)BLCKSZ* (blocknum % ((BlockNumber)RELSEG_SIZE));
732738

733-
(void)FilePrefetch(v->mdfd_vfd,seekpos,BLCKSZ,WAIT_EVENT_DATA_FILE_PREFETCH);
739+
Assert(seekpos< (off_t)BLCKSZ*RELSEG_SIZE);
740+
741+
nblocks_this_segment=
742+
Min(nblocks,
743+
RELSEG_SIZE- (blocknum % ((BlockNumber)RELSEG_SIZE)));
744+
745+
(void)FilePrefetch(v->mdfd_vfd,seekpos,BLCKSZ*nblocks_this_segment,
746+
WAIT_EVENT_DATA_FILE_PREFETCH);
747+
748+
blocknum+=nblocks_this_segment;
749+
nblocks-=nblocks_this_segment;
750+
}
734751
#endif/* USE_PREFETCH */
735752

736753
return true;

‎src/backend/storage/smgr/smgr.c

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -54,7 +54,7 @@ typedef struct f_smgr
5454
void(*smgr_zeroextend) (SMgrRelationreln,ForkNumberforknum,
5555
BlockNumberblocknum,intnblocks,boolskipFsync);
5656
bool(*smgr_prefetch) (SMgrRelationreln,ForkNumberforknum,
57-
BlockNumberblocknum);
57+
BlockNumberblocknum,intnblocks);
5858
void(*smgr_read) (SMgrRelationreln,ForkNumberforknum,
5959
BlockNumberblocknum,void*buffer);
6060
void(*smgr_write) (SMgrRelationreln,ForkNumberforknum,
@@ -547,9 +547,10 @@ smgrzeroextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
547547
* record).
548548
*/
549549
bool
550-
smgrprefetch(SMgrRelationreln,ForkNumberforknum,BlockNumberblocknum)
550+
smgrprefetch(SMgrRelationreln,ForkNumberforknum,BlockNumberblocknum,
551+
intnblocks)
551552
{
552-
returnsmgrsw[reln->smgr_which].smgr_prefetch(reln,forknum,blocknum);
553+
returnsmgrsw[reln->smgr_which].smgr_prefetch(reln,forknum,blocknum,nblocks);
553554
}
554555

555556
/*

‎src/include/storage/md.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -31,7 +31,7 @@ extern void mdextend(SMgrRelation reln, ForkNumber forknum,
3131
externvoidmdzeroextend(SMgrRelationreln,ForkNumberforknum,
3232
BlockNumberblocknum,intnblocks,boolskipFsync);
3333
externboolmdprefetch(SMgrRelationreln,ForkNumberforknum,
34-
BlockNumberblocknum);
34+
BlockNumberblocknum,intnblocks);
3535
externvoidmdread(SMgrRelationreln,ForkNumberforknum,BlockNumberblocknum,
3636
void*buffer);
3737
externvoidmdwrite(SMgrRelationreln,ForkNumberforknum,

‎src/include/storage/smgr.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -95,7 +95,7 @@ extern void smgrextend(SMgrRelation reln, ForkNumber forknum,
9595
externvoidsmgrzeroextend(SMgrRelationreln,ForkNumberforknum,
9696
BlockNumberblocknum,intnblocks,boolskipFsync);
9797
externboolsmgrprefetch(SMgrRelationreln,ForkNumberforknum,
98-
BlockNumberblocknum);
98+
BlockNumberblocknum,intnblocks);
9999
externvoidsmgrread(SMgrRelationreln,ForkNumberforknum,
100100
BlockNumberblocknum,void*buffer);
101101
externvoidsmgrwrite(SMgrRelationreln,ForkNumberforknum,

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