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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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32
src/backend/utils/misc/guc.c
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@ -196,6 +196,7 @@ static bool check_autovacuum_max_workers(int *newval, void **extra, GucSource so
static bool check_max_wal_senders(int *newval, void **extra, GucSource source);
static bool check_autovacuum_work_mem(int *newval, void **extra, GucSource source);
static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source);
static bool check_maintenance_io_concurrency(int *newval, void **extra, GucSource source);
static void assign_pgstat_temp_directory(const char *newval, void *extra);
static bool check_application_name(char **newval, void **extra, GucSource source);
static void assign_application_name(const char *newval, void *extra);
@ -2884,6 +2885,24 @@ static struct config_int ConfigureNamesInt[] =
check_effective_io_concurrency, NULL, NULL
},
{
{"maintenance_io_concurrency",
PGC_USERSET,
RESOURCES_ASYNCHRONOUS,
gettext_noop("A variant of effective_io_concurrency that is used for maintenance work."),
NULL,
GUC_EXPLAIN
},
&maintenance_io_concurrency,
#ifdef USE_PREFETCH
10,
#else
0,
#endif
0, MAX_IO_CONCURRENCY,
check_maintenance_io_concurrency, NULL, NULL
},
{
{"backend_flush_after", PGC_USERSET, RESOURCES_ASYNCHRONOUS,
gettext_noop("Number of pages after which previously performed writes are flushed to disk."),
@ -11466,6 +11485,19 @@ check_effective_io_concurrency(int *newval, void **extra, GucSource source)
return true;
}
static bool
check_maintenance_io_concurrency(int *newval, void **extra, GucSource source)
{
#ifndef USE_PREFETCH
if (*newval != 0)
{
GUC_check_errdetail("maintenance_io_concurrency must be set to 0 on platforms that lack posix_fadvise().");
return false;
}
#endif /* USE_PREFETCH */
return true;
}
static void
assign_pgstat_temp_directory(const char *newval, void *extra)
{