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Date:      Wed, 1 Aug 2018 21:27:31 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        bob prohaska <fbsd@www.zefox.net>, Mark Johnston <markj@FreeBSD.org>
Cc:        freebsd-arm@freebsd.org
Subject:   Re: RPI3 swap experiments ["was killed: out of swap space" with: "v_free_count: 5439, v_inactive_count: 1"]
Message-ID:  <EC74A5A6-0DF4-48EB-88DA-543FD70FEA07@yahoo.com>
In-Reply-To: <20180802015135.GC99523@www.zefox.net>
References:  <20180731153531.GA94742@www.zefox.net> <201807311602.w6VG2xcN072497@pdx.rh.CN85.dnsmgr.net> <20180731191016.GD94742@www.zefox.net> <23793AAA-A339-4DEC-981F-21C7CC4FE440@yahoo.com> <20180731231912.GF94742@www.zefox.net> <2222ABBD-E689-4C3B-A7D3-50AECCC5E7B2@yahoo.com> <20180801034511.GA96616@www.zefox.net> <201808010405.w7145RS6086730@donotpassgo.dyslexicfish.net> <6BFE7B77-A0E2-4FAF-9C68-81951D2F6627@yahoo.com> <20180802002841.GB99523@www.zefox.net> <20180802015135.GC99523@www.zefox.net>

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[I have a top-posted introduction here in reply
to a message listed at the bottom.]

Bob P. meet Mark J. Mark J. meet Bob P. I'm
hopinh you can help Bob P. use a patch that
you once published on the lists. This was from:

=
https://lists.freebsd.org/pipermail/freebsd-current/2018-June/069835.html

Bob P. has been having problems with an rpi3
based buildworld ending up with "was killed:
out of swap space" but when the swap partitions
do not seem to be heavily used (seen via swapinfo
or watching top).

[I will avoid the long, complicated history of
investigations here and also any past hypothesis
about contributing causes.]

Bob P. recently introduced Mark J.'s patch to report
the likes of: v_free_count: 5439, v_inactive_count: 1 .

The issue happens during time periods were simple
means of observation suggest that their is lots of
swap space available. Sorting by time (a looping
script was running, logging output, including
swapinfo output):

Wed Aug  1 18:08:10 PDT 2018

Device          1K-blocks     Used    Avail Capacity
/dev/da0b         1048576    28248  1020328     3%
/dev/mmcsd0s3b    1048576    28256  1020320     3%
Total             2097152    56504  2040648     3%

Aug  1 18:08:13 www kernel: v_free_count: 5439, v_inactive_count: 1

Wed Aug  1 18:08:21 PDT 2018

Device          1K-blocks     Used    Avail Capacity
/dev/da0b         1048576    31768  1016808     3%
/dev/mmcsd0s3b    1048576    31640  1016936     3%
Total             2097152    63408  2033744     3%

Aug  1 18:08:25 www kernel: pid 93301 (c++), uid 0, was killed: out of =
swap space

Wed Aug  1 18:08:35 PDT 2018

Device          1K-blocks     Used    Avail Capacity
/dev/da0b         1048576    24840  1023736     2%
/dev/mmcsd0s3b    1048576    25404  1023172     2%
Total             2097152    50244  2046908     2%

The above is a clean up of the output which had more
and had repeated information from the tail of a log
until it gets new messages. The original script was
something like:

#!/bin/sh
while true
do  gstat -abd -I 10s ; date ; swapinfo ; tail -n 2 /var/log/messages=20
done

I ran out of ability indicate what more to investigate. For
example I'm unsure of when to do the "sysctl vm" that you
[Mark J.] have suggested back in June. It is unlikely that
Bob P. will happen to be there when buildworld has the
kill(s) occur. When it happens in the build sequence is not
stable from one try to the next.

This introduction is a reply to the following.

On 2018-Aug-1, at 6:51 PM, bob prohaska <fbsd at www.zefox.net> wrote:

> The patch to report OOMA information did its job, very tersely. The =
console reported
> v_free_count: 5439, v_inactive_count: 1
> Aug  1 18:08:25 www kernel: pid 93301 (c++), uid 0, was killed: out of =
swap space
>=20
> The entire buildworld.log and gstat output are at
> http://www.zefox.net/~fbsd/rpi3/swaptests/r336877M/
>=20
> It appears that at 18:08:21 a write to the USB swap device took 530.5 =
ms,=20
> next top was killed and ten seconds later c++ was killed, _after_ da0b
> was no longer busy.
>=20
> This buildworld stopped a quite a bit earlier than usual; most of the =
time
> the buildworld.log file is close to 20 MB at the time OOMA acts. In =
this case
> it was around 13 MB. Not clear if that's of significance.
>=20
> If somebody would indicate whether this result is informative, and any =
possible
> improvements to the test, I'd be most grateful.=20

=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)




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