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Re: [HACKERS] high shared buffer and swap

From: PFC
Subject: Re: [HACKERS] high shared buffer and swap
Date: ,
Msg-id: op.utf9cpn7cigqcu@soyouz
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In response to: high shared buffer and swap  (Laurent Laborde)
Responses: Re: [HACKERS] high shared buffer and swap  (Laurent Laborde)
List: pgsql-performance

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high shared buffer and swap  (Laurent Laborde, )
 Re: high shared buffer and swap  (Greg Stark, )
  Re: [HACKERS] high shared buffer and swap  (Martijn van Oosterhout, )
 Re: high shared buffer and swap  (Scott Marlowe, )
 Re: [HACKERS] high shared buffer and swap  (PFC, )
  Re: [HACKERS] high shared buffer and swap  (Laurent Laborde, )
   Re: [HACKERS] high shared buffer and swap  (Matthew Wakeling, ) 
> An octocore server with 32GB of ram, running postgresql 8.3.6
> Running only postgresql, slony-I and pgbouncer.
>
> Just for testing purpose, i tried a setting with 26GB of shared_buffer.
>
> I quickly noticed that the performances wasn't very good and the
> server started to swap slowly but surely.
>  (but still up to 2000query/second as reported by pgfouine)
>
> It used all the 2GB of swap.
> I removed the server from production, added 10GB of swap and left it
> for the weekend with only slony and postgresql up to keep it in sync
> with the master database.
>
> This morning i found that the whole 12GB of swap were used :

    Hm, do you really need swap with 32Gb of RAM ?

    One could argue "yes but swap is useful to avoid out of memory errors".
    But if a loaded server starts to swap a lot, it is as good as dead
anyway...

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