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Re: Swapping in 7.4.3

From: "Matt Clark" <matt(at)ymogen(dot)net>
To: "'Scott Marlowe'" <smarlowe(at)qwest(dot)net>, <jim(dot)ewert(at)excite(dot)com>
Cc: <matthew(at)zeut(dot)net>, <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Swapping in 7.4.3
Date: 2004-07-16 07:35:32
Message-ID: 00b101c46b07$79a758d0$8300a8c0@solent (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
> This is normal.  My personal workstation has been up for 16 
> days, and it shows 65 megs used for swap.  The linux kernel 
> looks for things that haven't been accessed in quite a while 
> and tosses them into swap to free up the memory for other uses.
> This isn't PostgreSQL's fault, or anything elses.  It's how a 
> typical Unix kernel works.  I.e. you're seeing a problem that 
> simply isn't there.

Actually it (and other OSes) does slightly better than that.  It _copies_
the least recently used pages into swap, but leaves them in memory.  Then
when there really is a need to swap stuff out there is no need to actually
write to swap because it's already been done, and conversely if those pages
are wanted then they don't have to be read from disk because they were never
removed from memory.

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