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Enable IO concurrency on all systems

Browse Source 
Previously effective_io_concurrency and maintenance_io_concurrency could not
be set above 0 on machines without fadvise support. AIO enables IO concurrency
without such support, via io_method=worker.

Currently only subsystems using the read stream API will take advantage of
this. Other users of maintenance_io_concurrency (like recovery prefetching)
which leverage OS advice directly will not benefit from this change. In those
cases, maintenance_io_concurrency will have no effect on I/O behavior.

Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/CAAKRu_atGgZePo=_g6T3cNtfMf0QxpvoUh5OUqa_cnPdhLd=gw@mail.gmail.com
This commit is contained in:
Andres Freund
2025-03-30 19:14:55 -04:00
parent ae3df4b341
commit 2a5e709e72
10 changed files with 14 additions and 67 deletions
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8
src/backend/access/common/reloptions.c
View File

@@ -361,11 +361,7 @@ static relopt_int intRelOpts[] =
RELOPT_KIND_TABLESPACE,
ShareUpdateExclusiveLock
},
#ifdef USE_PREFETCH
-1, 0, MAX_IO_CONCURRENCY
#else
0, 0, 0
#endif
},
{
{
@@ -374,11 +370,7 @@ static relopt_int intRelOpts[] =
RELOPT_KIND_TABLESPACE,
ShareUpdateExclusiveLock
},
#ifdef USE_PREFETCH
-1, 0, MAX_IO_CONCURRENCY
#else
0, 0, 0
#endif
},
{
{

30
src/backend/commands/variable.c
View File

@@ -1145,7 +1145,6 @@ check_cluster_name(char **newval, void **extra, GucSource source)
void
assign_maintenance_io_concurrency(int newval, void *extra)
{
#ifdef USE_PREFETCH
/*
* Reconfigure recovery prefetching, because a setting it depends on
* changed.
@@ -1153,7 +1152,6 @@ assign_maintenance_io_concurrency(int newval, void *extra)
maintenance_io_concurrency = newval;
if (AmStartupProcess())
XLogPrefetchReconfigure();
#endif
}
/*
@@ -1249,34 +1247,6 @@ check_default_with_oids(bool *newval, void **extra, GucSource source)
return true;
}
bool
check_effective_io_concurrency(int *newval, void **extra, GucSource source)
{
#ifndef USE_PREFETCH
if (*newval != 0)
{
GUC_check_errdetail("\"%s\" must be set to 0 on platforms that lack support for issuing read-ahead advice.",
"effective_io_concurrency");
return false;
}
#endif /* USE_PREFETCH */
return true;
}
bool
check_maintenance_io_concurrency(int *newval, void **extra, GucSource source)
{
#ifndef USE_PREFETCH
if (*newval != 0)
{
GUC_check_errdetail("\"%s\" must be set to 0 on platforms that lack support for issuing read-ahead advice.",
"maintenance_io_concurrency");
return false;
}
#endif /* USE_PREFETCH */
return true;
}
bool
check_ssl(bool *newval, void **extra, GucSource source)
{

4
src/backend/utils/misc/guc_tables.c
View File

@@ -3235,7 +3235,7 @@ struct config_int ConfigureNamesInt[] =
&effective_io_concurrency,
DEFAULT_EFFECTIVE_IO_CONCURRENCY,
0, MAX_IO_CONCURRENCY,
check_effective_io_concurrency, NULL, NULL
NULL, NULL, NULL
},
{
@@ -3249,7 +3249,7 @@ struct config_int ConfigureNamesInt[] =
&maintenance_io_concurrency,
DEFAULT_MAINTENANCE_IO_CONCURRENCY,
0, MAX_IO_CONCURRENCY,
check_maintenance_io_concurrency, assign_maintenance_io_concurrency,
NULL, assign_maintenance_io_concurrency,
NULL
},

4
src/backend/utils/misc/postgresql.conf.sample
View File

@@ -198,8 +198,8 @@
# - I/O -
#backend_flush_after = 0 # measured in pages, 0 disables
#effective_io_concurrency = 16 # 1-1000; 0 disables prefetching
#maintenance_io_concurrency = 16 # 1-1000; 0 disables prefetching
#effective_io_concurrency = 16 # 1-1000; 0 disables issuing multiple simultaneous IO requests
#maintenance_io_concurrency = 16 # 1-1000; same as effective_io_concurrency
#io_max_combine_limit = 128kB # usually 1-128 blocks (depends on OS)
# (change requires restart)
#io_combine_limit = 128kB # usually 1-128 blocks (depends on OS)