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Introduce a maintenance_io_concurrency setting.

Browse Source 
Introduce a GUC and a tablespace option to control I/O prefetching, much
like effective_io_concurrency, but for work that is done on behalf of
many client sessions.

Use the new setting in heapam.c instead of the hard-coded formula
effective_io_concurrency + 10 introduced by commit 558a9165e0.  Go with
a default value of 10 for now, because it's a round number pretty close
to the value used for that existing case.

Discussion: https://postgr.es/m/CA%2BhUKGJUw08dPs_3EUcdO6M90GnjofPYrWp4YSLaBkgYwS-AqA%40mail.gmail.com
This commit is contained in:
Thomas Munro
2020-03-16 12:31:34 +13:00
parent b09ff53667
commit fc34b0d9de
12 changed files with 109 additions and 23 deletions
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16
src/backend/access/common/reloptions.c
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@ -349,6 +349,19 @@ static relopt_int intRelOpts[] =
-1, 0, MAX_IO_CONCURRENCY
#else
0, 0, 0
#endif
},
{
{
"maintenance_io_concurrency",
"Number of simultaneous requests that can be handled efficiently by the disk subsystem for maintenance work.",
RELOPT_KIND_TABLESPACE,
ShareUpdateExclusiveLock
},
#ifdef USE_PREFETCH
-1, 0, MAX_IO_CONCURRENCY
#else
0, 0, 0
#endif
},
{
@ -1700,7 +1713,8 @@ tablespace_reloptions(Datum reloptions, bool validate)
static const relopt_parse_elt tab[] = {
{"random_page_cost", RELOPT_TYPE_REAL, offsetof(TableSpaceOpts, random_page_cost)},
{"seq_page_cost", RELOPT_TYPE_REAL, offsetof(TableSpaceOpts, seq_page_cost)},
{"effective_io_concurrency", RELOPT_TYPE_INT, offsetof(TableSpaceOpts, effective_io_concurrency)}
{"effective_io_concurrency", RELOPT_TYPE_INT, offsetof(TableSpaceOpts, effective_io_concurrency)},
{"maintenance_io_concurrency", RELOPT_TYPE_INT, offsetof(TableSpaceOpts, maintenance_io_concurrency)}
};
return (bytea *) build_reloptions(reloptions, validate,