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Re: default resource limits

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: "Patches (PostgreSQL)" <pgsql-patches(at)postgresql(dot)org>
Subject: Re: default resource limits
Date: 2005-12-23 20:50:10
Message-ID: 43AC6302.1070202@dunslane.net (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches

er patch attached this time

Andrew Dunstan wrote:

>
>
> I wrote:
>
>>
>>
>> Tom Lane wrote:
>>
>>> Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
>>>  
>>>
>>>> Nearly everyone seems to agree that the default for max_fsm_pages 
>>>> is woefully low, so I would like to have the default for this set 
>>>> unconditionally to 200,000 rather than 20,000. The cost would be 
>>>> just over 1Mb of shared memory, if the docs are correct. 
>>>> Alternatively, we could put this into the mix that is calculated by 
>>>> initdb, scaling it linearly with shared_buffers (but with the 
>>>> default still at 200,000).
>>>>   
>>>
>>>
>>>
>>>  
>>>
>>>> I would also like to propose a more modest increase in 
>>>> max_connections and shared_buffers by a factor of 3.
>>>>   
>>>
>>>
>>>
>>> I don't mind having initdb try larger values to see if they work, but
>>> if you are suggesting that we try to force adoption of larger settings
>>> I'll resist it.
>>>  
>>>
>>
>> OK, works for me. The only thing I suggested might be set in stone 
>> was max_fsm_pages; I always envisioned the others being tested as now 
>> by initdb.
>>
>>> "Factor of three" seems mighty weird.  The existing numbers (100 and 
>>> 1000)
>>> at least have the defensibility of being round.
>>>
>>>      
>>>
>>
>> What numbers would you like? If what I suggested seems odd, how about 
>> targets of 400 connections, 4000 shared_buffers and 200,000 
>> max_fsm_pages?
>>
>>
>
>
> Here's a patch that does what I had in mind. On my modest workstation 
> it tops out at 400 connections and 2500/125000 
> shared_buffers/max_fsm_pages. An idle postmaster with these settings 
> consumed less than 4% of the 380Mb of memory, according to top, making 
> it still dwarfed by X, mozilla, apache and amavisd among other memory 
> hogs.
>
> Comments welcome.
>
> cheers
>
> andrew
>
> ---------------------------(end of broadcast)---------------------------
> TIP 5: don't forget to increase your free space map settings
>

Attachment: revlimits.diff
Description: text/x-patch (3.3 KB)

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