From fc34b0d9de27ab5ac2887da00b3892bdabd89e45 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Mon, 16 Mar 2020 12:31:34 +1300 Subject: Introduce a maintenance_io_concurrency setting. 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 558a9165e08. 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 --- src/backend/utils/misc/guc.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'src/backend/utils/misc/guc.c') diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 326e773b25f..68082315acd 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -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) { -- cgit v1.2.3