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Date:      Wed, 29 Jul 2015 22:00:12 -0700
From:      Doug Hardie <bc979@lafn.org>
To:        Chris H <bsd-lists@bsdforge.com>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: Swap Usage
Message-ID:  <DE6B4BB1-7863-42E2-8EC9-EB4239CD7C91@lafn.org>
In-Reply-To: <f4a3f3c22a83638087162328c5c8702b@ultimatedns.net>
References:  <BCA67F7E-676A-4226-83A0-84229948895E@lafn.org> <f4a3f3c22a83638087162328c5c8702b@ultimatedns.net>

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> On 29 July 2015, at 18:57, Chris H <bsd-lists@bsdforge.com> wrote:
>=20
> On Wed, 29 Jul 2015 17:41:33 -0700 Doug Hardie <bc979@lafn.org> wrote
>=20
>> I have several FreeBSD 9.3 systems that are using swap and I can=E2=80=99=
t figure
>> out what is doing it.  The key system has 6GB swap and currently it =
has over
>> 2GB in use.  ps shows only a kernel module [intr] with a W status.  =
Obviously
>> that isn=E2=80=99t using the space.  No other process shows a W in =
its status.  I
>> suspect this is somewhat related to the use of mmap in one =
application.=20
>> However, all of the mmaps in that application are file backed and =
thus
>> shouldn=E2=80=99t use swap.  How do I figure out what that swap space =
is being used
>> for?=20
> Maybe top(1)?
> top -P
> for example. At least you could see who's chewing all your memory. =
Which
> should be a good clue as to who's responsible for swap usage.

UFS although I don=E2=80=99t see how that could make a difference.  Swap =
doesn=E2=80=99t use a regular file system.  However, the kernel must =
track the actual usage using something like a simple file system.  There =
must be a way to investigate it.

Top doesn=E2=80=99t show anything unusual.  The most VM used is by the =
process that uses a lot of mmap space that is all file backed.  If it =
was another process that was partially swapped then the ps status should =
show a W.  Only the one does.=



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