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Commitdf955c6

Browse files
author
Daniel Shelepanov
committed
memory page locality
1 parent6a8d748 commitdf955c6

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3 files changed

+44
-7
lines changed

3 files changed

+44
-7
lines changed

‎engine.c‎

Lines changed: 32 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -686,6 +686,35 @@ ptrack_walkdir(const char *path, Oid tablespaceOid, Oid dbOid)
686686
FreeDir(dir);/* we ignore any error here */
687687
}
688688

689+
/*
690+
* Get a second position within ptrack map so that it fits
691+
* within the same cache line.
692+
*/
693+
size_t
694+
get_slot2(size_tslot1,uint64hash) {
695+
size_tcache_line_ep;// ending point of a cache line
696+
size_tcache_line_sp;// starting point of a cache line
697+
size_tcache_line_interval;
698+
size_tslot2;
699+
700+
/* Get the ending point of a cache line within entries[]. */
701+
cache_line_ep= (CACHE_LINE_ALIGN(offsetof(PtrackMapHdr,entries)+slot1*sizeof(XLogRecPtr))
702+
- offsetof(PtrackMapHdr,entries)) /sizeof(XLogRecPtr);
703+
/* handling an overflow beyond the entries boundary */
704+
cache_line_ep=cache_line_ep>PtrackContentNblocks ?PtrackContentNblocks :cache_line_ep;
705+
706+
/* Get the starting point of a cache line within entries[]. */
707+
cache_line_sp=cache_line_ep-ENTRIES_PER_LINE;
708+
709+
/* Handling overflow below zero (sp then must be larger than ep) */
710+
cache_line_sp=cache_line_sp>cache_line_ep ?0 :cache_line_sp;
711+
712+
cache_line_interval=cache_line_ep-cache_line_sp;
713+
slot2= (size_t)(cache_line_sp+ (((hash <<32) | (hash >>32)) %cache_line_interval));
714+
slot2= (slot1==slot2) ? ((slot1+1) %cache_line_interval) :slot2;
715+
returnslot2;
716+
}
717+
689718
/*
690719
* Mark modified block in ptrack_map.
691720
*/
@@ -738,7 +767,6 @@ ptrack_mark_block(RelFileNodeBackend smgr_rnode,
738767
* We use pg_atomic_uint64 here only for alignment purposes, because
739768
* pg_atomic_uint64 is forcedly aligned on 8 bytes during the MSVC build.
740769
*/
741-
pg_atomic_uint32old_lsn;
742770
pg_atomic_uint32old_init_lsn;
743771

744772
if (ptrack_map_size==0
@@ -753,7 +781,7 @@ ptrack_mark_block(RelFileNodeBackend smgr_rnode,
753781

754782
hash=BID_HASH_FUNC(bid);
755783
slot1= (size_t)(hash %PtrackContentNblocks);
756-
slot2=(size_t)(((hash <<32) | (hash >>32)) %PtrackContentNblocks);
784+
slot2=get_slot2(slot1,hash);
757785

758786
bid.blocknum=InvalidBlockNumber;
759787
hash=BID_HASH_FUNC(bid);
@@ -807,8 +835,8 @@ XLogRecPtr ptrack_read_file_maxlsn(RelFileNode rnode, ForkNumber forknum)
807835
if (slot2<slot1)
808836
swap_slots(&slot1,&slot2);
809837

810-
update_lsn1=pg_atomic_read_u64(&ptrack_map->entries[slot1]);
811-
update_lsn2=pg_atomic_read_u64(&ptrack_map->entries[slot2]);
838+
update_lsn1=pg_atomic_read_u32(&ptrack_map->entries[slot1]);
839+
update_lsn2=pg_atomic_read_u32(&ptrack_map->entries[slot2]);
812840

813841
returnupdate_lsn1==update_lsn2 ?update_lsn1 :InvalidXLogRecPtr;
814842
}

‎engine.h‎

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -40,6 +40,14 @@
4040
*/
4141
#definePTRACK_BUF_SIZE ((uint64) 8000)
4242

43+
/*
44+
* A reasonable assumption for most systems. Postgres core
45+
* leverages the same value for this purpose.
46+
*/
47+
#defineCACHE_LINE_SIZE64
48+
#defineCACHE_LINE_ALIGN(LEN)TYPEALIGN(CACHE_LINE_SIZE, (LEN))
49+
#defineENTRIES_PER_LINE(CACHE_LINE_SIZE/sizeof(XLogRecPtr))
50+
4351
/* Ptrack magic bytes */
4452
#definePTRACK_MAGIC "ptk"
4553
#definePTRACK_MAGIC_SIZE 4
@@ -122,6 +130,7 @@ extern XLogRecPtr ptrack_read_file_maxlsn(RelFileNode smgr_rnode,
122130
ForkNumberforknum);
123131

124132
externboolis_cfm_file_path(constchar*path);
133+
externsize_tget_slot2(size_tslot1,uint64hash);
125134
#ifdefPGPRO_EE
126135
externoff_tget_cfs_relation_file_decompressed_size(RelFileNodeBackendrnode,
127136
constchar*fullpath,ForkNumberforknum);

‎ptrack.c‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -467,8 +467,8 @@ ptrack_filelist_getnext(PtScanCtx * ctx)
467467
if (maxlsn<ctx->lsn)
468468
{
469469
elog(DEBUG3,"ptrack: skip file %s: maxlsn is %X/%X, expected %X/%X",
470-
fullpath, (uint32) (maxlsn >>32), (uint32)maxlsn,
471-
(uint32) (ctx->lsn >>32), (uint32)ctx->lsn);
470+
fullpath, (uint16) (maxlsn >>16), (uint16)maxlsn,
471+
(uint16) (ctx->lsn >>16), (uint16)ctx->lsn);
472472

473473
/* Try the next one */
474474
gotoget_next;
@@ -671,7 +671,7 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
671671
/* Only probe the second slot if the first one is marked */
672672
if (within_ptrack_map&&lsn_diff(ctx->lsn,update_lsn1) <=0)
673673
{
674-
slot2=(size_t)(((hash <<32) | (hash >>32)) %PtrackContentNblocks);
674+
slot2=get_slot2(slot1,hash);
675675
update_lsn2=pg_atomic_read_u32(&ptrack_map->entries[slot2]);
676676

677677
if (update_lsn2!=InvalidXLogRecPtr)

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