On Mon, Mar 17, 2025 at 2:55 PM Andres Freund <and...@anarazel.de> wrote: > > On 2025-03-17 14:52:02 -0400, Melanie Plageman wrote: > > I don't feel strongly that we need to be as rigorous for > > maintenance_io_concurrency, but I'm also not sure 160 seems reasonable > > (which would be the same ratio as before). > > I'd lean towards just setting them to the same value for now.
Cool, here's the patch I intend to commit. I had a bit of trouble clearly explaining the situation in the commit message which is why I didn't directly commit it. If no one has ideas on how to clarify it by tomorrow, I'll just push it. - Melanie
From babd220052bcef744e38302e35c6eaee8364027d Mon Sep 17 00:00:00 2001 From: Melanie Plageman <melanieplage...@gmail.com> Date: Mon, 17 Mar 2025 17:08:49 -0400 Subject: [PATCH v1] Increase default maintenance_io_concurrency to 16 Since its introduction in fc34b0d9de27a, the default maintenance_io_concurrency has been larger than the default effective_io_concurrency. This made sense at the time because maintenance_io_concurrency controlled I/O prefetching done on behalf of many client sessions (such as in recovery). ff79b5b2ab increased effective_io_concurrency to 16, so we'll increase maintenance_io_concurrency as well. For now, though, we'll keep the defaults of effective_io_concurrency and maintenance_io_concurrency equal to one another (16). Since 9256822608f and c3e775e608f, maintenance_io_concurrency also controls the I/O concurrency of each vacuum worker. Since many autovacuum workers may be simultaneously issuing I/Os, an appropriate default value for maintenance_io_concurrency is likely closer to that of the default effective_io_concurrency rather than the previous ratio (10x). Suggested-by: Jakub Wartak <jakub.war...@enterprisedb.com> Discussion: https://postgr.es/m/CAKZiRmxdHQaU%2B2Zpe6d%3Dx%3D0vigJ1sfWwwVYLJAf%3Dud_wQ_VcUw%40mail.gmail.com --- doc/src/sgml/config.sgml | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 2 +- src/include/storage/bufmgr.h | 2 +- 3 files changed, 6 insertions(+), 6 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 3d62c8bd274..a3aae67746b 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -2617,10 +2617,10 @@ include_dir 'conf.d' for maintenance work that is done on behalf of many client sessions. </para> <para> - The default is 10 on supported systems, otherwise 0. This value can - be overridden for tables in a particular tablespace by setting the - tablespace parameter of the same name (see - <xref linkend="sql-altertablespace"/>). + The default is <literal>16</literal> on supported systems, otherwise + <literal>0</literal>. This value can be overridden for tables in a + particular tablespace by setting the tablespace parameter of the same + name (see <xref linkend="sql-altertablespace"/>). </para> </listitem> </varlistentry> diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 8de86e0c945..613d5b3ee39 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -199,7 +199,7 @@ #backend_flush_after = 0 # measured in pages, 0 disables #effective_io_concurrency = 16 # 1-1000; 0 disables prefetching -#maintenance_io_concurrency = 10 # 1-1000; 0 disables prefetching +#maintenance_io_concurrency = 16 # 1-1000; 0 disables prefetching #io_combine_limit = 128kB # usually 1-32 blocks (depends on OS) # - Worker Processes - diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h index 79a89f87fcc..7f5def6bada 100644 --- a/src/include/storage/bufmgr.h +++ b/src/include/storage/bufmgr.h @@ -153,7 +153,7 @@ extern PGDLLIMPORT bool track_io_timing; /* only applicable when prefetching is available */ #ifdef USE_PREFETCH #define DEFAULT_EFFECTIVE_IO_CONCURRENCY 16 -#define DEFAULT_MAINTENANCE_IO_CONCURRENCY 10 +#define DEFAULT_MAINTENANCE_IO_CONCURRENCY 16 #else #define DEFAULT_EFFECTIVE_IO_CONCURRENCY 0 #define DEFAULT_MAINTENANCE_IO_CONCURRENCY 0 -- 2.34.1
