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[PATCH 3/9] Optimize allocations in bringetbitmap 2+ messages / 2 participants [nested] [flat]
* [PATCH 3/9] Optimize allocations in bringetbitmap @ 2020-09-13 10:12 Tomas Vondra <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Tomas Vondra @ 2020-09-13 10:12 UTC (permalink / raw) The bringetbitmap function allocates memory for various purposes, which may be quite expensive, depending on the number of scan keys. Instead of allocating them separately, allocate one bit chunk of memory an carve it into smaller pieces as needed - all the pieces have the same lifespan, and it saves quite a bit of CPU and memory overhead. Author: Tomas Vondra <[email protected]> Discussion: https://postgr.es/m/[email protected] --- src/backend/access/brin/brin.c | 62 +++++++++++++++++++++++++++------- 1 file changed, 49 insertions(+), 13 deletions(-) diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c index 14da9ed17f..c7f7175a2a 100644 --- a/src/backend/access/brin/brin.c +++ b/src/backend/access/brin/brin.c @@ -373,6 +373,9 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm) int *nkeys, *nnullkeys; int keyno; + char *ptr; + Size len; + char *tmp PG_USED_FOR_ASSERTS_ONLY; opaque = (BrinOpaque *) scan->opaque; bdesc = opaque->bo_bdesc; @@ -398,11 +401,50 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm) * Make room for per-attribute lists of scan keys that we'll pass to the * consistent support procedure. We keep null and regular keys separate, * so that we can easily pass regular keys to the consistent function. + * + * To reduce the allocation overhead, we allocate one big chunk and then + * carve it into smaller arrays ourselves. All the pieces have exactly + * the same lifetime, so that's OK. */ - keys = palloc0(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts); - nullkeys = palloc0(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts); - nkeys = palloc0(sizeof(int) * bdesc->bd_tupdesc->natts); - nnullkeys = palloc0(sizeof(int) * bdesc->bd_tupdesc->natts); + len = + /* regular keys */ + MAXALIGN(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts) + + MAXALIGN(sizeof(ScanKey) * scan->numberOfKeys) * bdesc->bd_tupdesc->natts + + MAXALIGN(sizeof(int) * bdesc->bd_tupdesc->natts) + + /* NULL keys */ + MAXALIGN(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts) + + MAXALIGN(sizeof(ScanKey) * scan->numberOfKeys) * bdesc->bd_tupdesc->natts + + MAXALIGN(sizeof(int) * bdesc->bd_tupdesc->natts); + + ptr = palloc(len); + tmp = ptr; + + keys = (ScanKey **) ptr; + ptr += MAXALIGN(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts); + + nullkeys = (ScanKey **) ptr; + ptr += MAXALIGN(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts); + + nkeys = (int *) ptr; + ptr += MAXALIGN(sizeof(int) * bdesc->bd_tupdesc->natts); + + nnullkeys = (int *) ptr; + ptr += MAXALIGN(sizeof(int) * bdesc->bd_tupdesc->natts); + + for (int i = 0; i < bdesc->bd_tupdesc->natts; i++) + { + keys[i] = (ScanKey *) ptr; + ptr += MAXALIGN(sizeof(ScanKey) * scan->numberOfKeys); + + nullkeys[i] = (ScanKey *) ptr; + ptr += MAXALIGN(sizeof(ScanKey) * scan->numberOfKeys); + } + + Assert(tmp + len == ptr); + + /* zero the number of keys */ + memset(nkeys, 0, sizeof(int) * bdesc->bd_tupdesc->natts); + memset(nnullkeys, 0, sizeof(int) * bdesc->bd_tupdesc->natts); /* * Preprocess the scan keys - split them into per-attribute arrays. @@ -438,9 +480,9 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm) { FmgrInfo *tmp; - /* No key/null arrays for this attribute. */ - Assert((keys[keyattno - 1] == NULL) && (nkeys[keyattno - 1] == 0)); - Assert((nullkeys[keyattno - 1] == NULL) && (nnullkeys[keyattno - 1] == 0)); + /* First time we see this attribute, so no key/null keys. */ + Assert(nkeys[keyattno - 1] == 0); + Assert(nnullkeys[keyattno - 1] == 0); tmp = index_getprocinfo(idxRel, keyattno, BRIN_PROCNUM_CONSISTENT); @@ -451,17 +493,11 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm) /* Add key to the proper per-attribute array. */ if (key->sk_flags & SK_ISNULL) { - if (!nullkeys[keyattno - 1]) - nullkeys[keyattno - 1] = palloc0(sizeof(ScanKey) * scan->numberOfKeys); - nullkeys[keyattno - 1][nnullkeys[keyattno - 1]] = key; nnullkeys[keyattno - 1]++; } else { - if (!keys[keyattno - 1]) - keys[keyattno - 1] = palloc0(sizeof(ScanKey) * scan->numberOfKeys); - keys[keyattno - 1][nkeys[keyattno - 1]] = key; nkeys[keyattno - 1]++; } -- 2.26.2 --------------0E72B707603BED22B4040825 Content-Type: text/x-patch; charset=UTF-8; name="0002-Move-IS-NOT-NULL-handling-from-BRIN-support-20210211.patch" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename*0="0002-Move-IS-NOT-NULL-handling-from-BRIN-support-20210211.pa"; filename*1="tch" ^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Remove support for old realpath() API @ 2024-08-12 14:35 Tom Lane <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Tom Lane @ 2024-08-12 14:35 UTC (permalink / raw) To: Thomas Munro <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; Heikki Linnakangas <[email protected]>; pgsql-hackers I wrote: > Peter Eisentraut <[email protected]> writes: >> Tom had tested this on and found that it does actually work on AIX 7.1 >> and 7.3 but the documentation is wrong. > I too have a distinct recollection of having tested this (using the > gcc compile farm machines), but I cannot find anything saying so in > the mailing list archives. I can go check it again, I guess. I can confirm that the attached program works on cfarm111 (AIX 7.1) and cfarm119 (AIX 7.3), though "man realpath" denies it on both systems. I also found leftover test files demonstrating that I checked this same point on Apr 26 2024, so I'm not sure why that didn't turn up in a mail list search. regards, tom lane Attachments: [text/x-c] testrealpath.c (257B, ../../[email protected]/2-testrealpath.c) download | inline: #include <stdio.h> #include <stdlib.h> int main(int argc, char **argv) { char *pth = realpath(argv[1], NULL); if (pth) { printf("successfully resolved \"%s\" as \"%s\"\n", argv[1], pth); free(pth); } else perror("realpath"); return 0; } ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2024-08-12 14:35 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2020-09-13 10:12 [PATCH 3/9] Optimize allocations in bringetbitmap Tomas Vondra <[email protected]> 2024-08-12 14:35 Re: Remove support for old realpath() API Tom Lane <[email protected]>
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