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Date:      Thu, 31 Jul 2014 01:15:16 +0100
From:      RW <rwmaillists@googlemail.com>
To:        freebsd-hackers@freebsd.org
Subject:   Re: FreeBSD 10 swapping Idle processes :/
Message-ID:  <20140731011516.21b1261d@gumby.homeunix.com>
In-Reply-To: <53D97C71.3050806@freebsd.org>
References:  <53D962A7.5090105@gmail.com> <53D97C71.3050806@freebsd.org>

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On Wed, 30 Jul 2014 19:14:57 -0400
Allan Jude wrote:

> On 2014-07-30 17:24, Adi wrote:
> > Hello
> > 
> > i7-4770 , 32 GB RAM,  FreeBSD 10.0-RELEASE-p7,  AMD64, UFS2
> > 
> > Problem: Many idle processes is swapping :(
> > 

> 
> That looks odd, the output of top shows 0 swap usage, but also 0
> resident memory for most of the processes...
> 

My guess would be that these processes have had all their pages
deactivated to accelerate their paging-out. Linux uses the terms
swapping and paging interchangeably to mean paging. In FreeBSD
swapping refers to the management of paging at the process level - in
some cases it's more efficient to page-out all the memory from some
idle or less active processes. 

I did think swapping was only used under abnormal memory shortage, but
I just reproduced this by dd'ing a 16 GB file to tmpfs (with 16GB RAM,
and 16GB swap). Some processes were marked as swapped before any
actual paging occurred. 



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