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* vm.overcommit_ratio
@ 2024-12-26 07:44 PG Doc comments form <noreply@postgresql.org>
2025-01-08 08:21 ` Re: vm.overcommit_ratio Peter Eisentraut <peter@eisentraut.org>
0 siblings, 1 reply; 2+ messages in thread
From: PG Doc comments form @ 2024-12-26 07:44 UTC (permalink / raw)
To: pgsql-docs@lists.postgresql.org; +Cc: splarv@ya.ru
The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/16/kernel-resources.html
Description:
PostgreSQL documentation point to kernel documentation for info about
vm.overcommit_ratio. But kernel documentation slightly incorrect, so may be
write slightly more here. Kernel documentation said:
The total address space commit
for the system is not permitted to exceed swap + a
configurable amount (default is 50%) of physical RAM.
Where 50% is the default for vm.overcommit_ratio. But really not "physical
RAM" is taken in case when using hugepage memory (common practice for
postgresql). For instance I have 1TiB physical memory and 800 GiB is
reserved for hugepage (1GiB pagesize). "50% of physical RAM" will be not 500
GiB, as expected, but roughly 100GiB=0.5*(1000-800), and commit limit will
be 100GiB+swap size.
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: vm.overcommit_ratio
2024-12-26 07:44 vm.overcommit_ratio PG Doc comments form <noreply@postgresql.org>
@ 2025-01-08 08:21 ` Peter Eisentraut <peter@eisentraut.org>
0 siblings, 0 replies; 2+ messages in thread
From: Peter Eisentraut @ 2025-01-08 08:21 UTC (permalink / raw)
To: splarv@ya.ru; pgsql-docs@lists.postgresql.org
On 26.12.24 08:44, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
>
> Page: https://www.postgresql.org/docs/16/kernel-resources.html
> Description:
>
> PostgreSQL documentation point to kernel documentation for info about
> vm.overcommit_ratio. But kernel documentation slightly incorrect, so may be
> write slightly more here.
Shouldn't we then get the kernel documentation corrected?
What is your source for this information?
^ permalink raw reply [nested|flat] 2+ messages in thread
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