Re: Increase default effective_cache_size? - Mailing list pgsql-hackers

From Andrew Dunstan
Subject Re: Increase default effective_cache_size?
Date
Msg-id 4517C8BD.2080908@dunslane.net
Whole thread Raw
In response to Re: Increase default effective_cache_size?  (Teodor Sigaev <teodor@sigaev.ru>)
Responses Re: Increase default effective_cache_size?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers

Teodor Sigaev wrote:
>> current default of 1000 pages (8Mb) seems really pretty silly for modern
>> machines; we could certainly set it to 10 times that without problems,
>> and maybe much more.  Thoughts?
>
> May be, set by default effective_cache_size equal to number of shared 
> buffers?
> If pgsql is configured to  use quarter  or half of total memory for 
> shared buffer, then effective_cache_size will have good approximation...
>
>


Initdb does not currently make any attempt to discover the extent of 
physical or virtual memory, it simply tries to start postgres with 
certain shared_buffer settings, starting at 4000, and going down until 
we get a success.

max_fsm_pages is now fixed proportionally with shared_buffers, and I 
guess we could do something similar with effective_cache_size, but since 
IIRC this doesn't involve shared memory I'm inclined to agree with Tom 
that it should just be fixed at some substantially higher level.

cheers

andrew




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