Re: Linux2.6 overcommit behaviour

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Linux2.6 overcommit behaviour
Date: 2003-08-30 15:16:02
Message-ID: 3F50BFB2.3000701@dunslane.net
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You need to allow some head room, I should think. Actually, the
equivalent of the previously discussed paranoid mode would be to set the
percentage to 0, i.e. ensure you can put every page in swap. If you say
50% then the chances of your running out of room are exceedingly small.

andrew

Bruce Momjian wrote:

>Shridhar Daithankar wrote:
>
>
>>Hi all,
>>
>>Following is from Documentation/vm/overcommit-accounting
>>-------------
>>2 - (NEW) strict overcommit. The total address space commit
>> for the system is not permitted to exceed swap + a
>> configurable percentage (default is 50) of physical RAM.
>> Depending on the percentage you use, in most situations
>> this means a process will not be killed while accessing
>> pages but will receive errors on memory allocation as
>> appropriate.
>>
>>
>
>It is strange to choose 50% of RAM plus swap (what if your spam is
>small). I thought it would be 100% of RAM plus the swap that exceeds RAM
>size.
>
>
>

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