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Date:      Thu, 21 Jun 2018 07:51:48 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        freebsd-arm <freebsd-arm@freebsd.org>, bob prohaska <fbsd@www.zefox.net>
Subject:   Re: GPT vs MBR for swap devices
Message-ID:  <10CAC122-399D-459E-9153-ABD7E753777E@yahoo.com>
In-Reply-To: <1D86911D-20D1-494A-822B-1C07C5598CB1@yahoo.com>
References:  <25F1A4BA-FBFC-4C32-85DD-5F5BA71A2B1A@yahoo.com> <20180620023253.GA89924@www.zefox.net> <a232ed45-a9a9-1017-72ed-720a6c7a8f03@sentry.org> <1D86911D-20D1-494A-822B-1C07C5598CB1@yahoo.com>

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[When I send to Trev, my Email is rejected as spam. This happens
even for a direct send without the list address or other addresses
involved. I do not see evidence of why in what I get back in the
"unable to deliver" notice. The below is just a resend with this
note added: no new technical content.]

On 2018-Jun-21, at 7:16 AM, Mark Millard <marklmi at yahoo.com> wrote:

> On 2018-Jun-21, at 12:28 AM, Trev <freebsd-arm at sentry.org> wrote:
>=20
>> I gave in and bought an Raspberry Pi 3B+ and now I've been bitten by =
Bob's OOM assassin too...
>>=20
>> % gpart show
>> =3D>      63  31116225  mmcsd0  MBR  (15G)
>>       63      2016          - free -  (1.0M)
>>     2079    102312       1  fat32lba  [active]  (50M)
>>   104391  31008825       2  freebsd  (15G)
>> 31113216      3072          - free -  (1.5M)
>>=20
>> =3D>       0  31008825  mmcsd0s2  BSD  (15G)
>>        0        57            - free -  (29K)
>>       57  31008768         1  freebsd-ufs  (15G)
>>=20
>> =3D>      40  60567472  da0  GPT  (29G)
>>       40   4194304    1  freebsd-swap  (2.0G)
>>  4194344  56373168    2  freebsd-ufs  (27G)
>>=20
>> % cat /etc/fstab
>> # Custom /etc/fstab for FreeBSD embedded images
>> /dev/ufs/rootfs   /       ufs     rw,noatime      1       1
>> /dev/msdosfs/MSDOSBOOT /boot/msdos msdosfs rw,noatime 0 0
>> md1 /tmp mfs rw,noatime,-s100m 0 0
>> md2 /var/log mfs rw,noatime,-s15m 0 0
>> md3 /var/tmp mfs rw,noatime,-s15m 0 0
>> /dev/ufs/swap   none    swap    sw      0       0
>> /dev/ufs/usr    /usr    ufs     rw,noatime      2       2
>>=20
>> da0 is a brand new 32G EMTEC USB2 memory key housing /usr and swap =
partitions.
>>=20
>> FreeBSD 12.0-CURRENT #0 r335317: Mon Jun 18 17:37:04 UTC 2018 =
root@releng3.nyi.freebsd.org:/usr/obj/usr/src/arm64.aarch64/sys/GENERIC =
arm64
>>=20
>> make -j4 buildworld resulted in:
>>=20
>> Jun 21 17:05:12 rpi3 kernel: pid 10326 (c++), uid 0, was killed: out =
of swap space
>> --- CodeGen/AsmPrinter/CodeViewDebug.o ---
>> c++: error: unable to execute command: Killed
>> c++: error: clang frontend command failed due to signal (use -v to =
see invocation)
>> FreeBSD clang version 6.0.0 (tags/RELEASE_600/final 326565) (based on =
LLVM 6.0.0)
>> Target: aarch64-unknown-freebsd12.0
>> Thread model: posix
>> InstalledDir: /usr/bin
>> c++: note: diagnostic msg: PLEASE submit a bug report to =
https://bugs.freebsd.org/submit/ and include the crash backtrace, =
preprocessed source, and associated run script.
>> c++: note: diagnostic msg:
>>=20
>> I happened to have been watching top (5 second interval) at the time =
and of the 2G swap, only 45M was shown to be in use.
>=20
> Are you getting errors such as those listed in:
>=20
> https://lists.freebsd.org/pipermail/freebsd-arm/2018-June/018091.html
>=20
> ? If not, your context may be a better test case than Bob P.'s.
>=20
> It looks like the latest from Bob P. is that when his /dev/da0
> is not used for swap (and so has far less I/O) his builds finish,
> apparently without logging errors:
>=20
> =
http://www.zefox.net/~fbsd/rpi3/swaptests/newtests/1gbsdflash_1.3gbusbmech=
anical_swapinfo/readme
>=20
> where he writes:
>=20
>> This test used the 1 GB SD flash swap partition plus a 1.3 GB =
partition=20
>> on a USB mechanical disk. The -j4 buildworld ran to completion =
without
>> obvious errors, serving mostly to suggest there's nothing wrong with=20=

>> the read/write behavior of /dev/da0, the USB flash drive holding /usr
>> and with it /usr/obj.
>=20
>=20
> (I do not share his conclusion about /dev/da0 based on the smaller
> amount of I/O when it was not used for swapping.)
>=20
> As far as I know the swap system is far more dependent on timely
> I/O than the other I/O involved in a build.
>=20
> Even without errors considered Bob was getting things like the
> large ms/w figures below:
>=20
>> Mon Jun 18 09:42:05 PDT 2018
>> Device          1K-blocks     Used    Avail Capacity
>> /dev/da0b         1048576     3412  1045164     0%
>> /dev/mmcsd0s3b    1048576     3508  1045068     0%
>> Total             2097152     6920  2090232     0%
>> dT: 10.043s  w: 10.000s
>> L(q)  ops/s    r/s   kBps   ms/r    w/s   kBps   ms/w    d/s   kBps   =
ms/d   %busy Name
>>   0      0      0      0    0.0      0      9   10.8      0      0    =
0.0    0.1  mmcsd0
>>  46      0      0      0    0.0      0     16  12355      0      0    =
0.0   85.9  da0
>>   0      0      0      0    0.0      0      9   10.8      0      0    =
0.0    0.1  mmcsd0s3
>>   0      0      0      0    0.0      0      9   10.8      0      0    =
0.0    0.1  mmcsd0s3a
>>  33      0      0      0    0.0      0     22  12318      0      0    =
0.0  114.1  da0d
>> Mon Jun 18 09:42:25 PDT 2018
>> Device          1K-blocks     Used    Avail Capacity
>> /dev/da0b         1048576     3412  1045164     0%
>> /dev/mmcsd0s3b    1048576     3508  1045068     0%
>> Total             2097152     6920  2090232     0%
>=20
>=20
> Are you getting such during the swapping activity?
>=20
> Overall: the I/O errors (if any) and the large ms/w (or ms/r) figures
> are things to look for.

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




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