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Date:      Sat, 30 Jun 2018 23:42:00 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        bob prohaska <fbsd@www.zefox.net>
Cc:        Trev <freebsd-arm@sentry.org>, freebsd-arm@freebsd.org
Subject:   Re: RPI3 swap experiments
Message-ID:  <5202FC09-B76A-4E03-BC2F-8144B505E0BA@yahoo.com>
In-Reply-To: <20180701025354.GA49303@www.zefox.net>
References:  <20180627054027.GA22144@www.zefox.net> <CC72E766-03CB-476C-8F2B-DAAC266CE63D@yahoo.com> <20180627194217.GA27793@www.zefox.net> <C6303FC5-B412-472C-98E4-9A1E45C38535@yahoo.com> <20180628022457.GA30110@www.zefox.net> <7B9D272D-3EDE-46FA-8A1C-AEE65047167C@yahoo.com> <20180628163328.GA33408@www.zefox.net> <51e208b4-9f14-58f7-1e70-6ef8db2c0bed@sentry.org> <20180629155131.GA35717@www.zefox.net> <f842b145-c79b-161d-5282-992212f8296f@sentry.org> <20180701025354.GA49303@www.zefox.net>

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On 2018-Jun-30, at 7:53 PM, bob prohaska <fbsd at www.zefox.net> wrote:

> On Sun, Jul 01, 2018 at 09:42:15AM +1000, Trev wrote:
>> bob prohaska wrote on 30/06/2018 01:51:
>>> On Fri, Jun 29, 2018 at 10:28:25PM +1000, Trev wrote:
>>>> 
>>>> Jun 29 20:20:35 rpi3 kernel: pid 66844 (c++), uid 0, was killed: out of
>>>> swap space
>>>> 
>>>> At the time of "out of swap" only 157M of the 4G swap was in use. The
>>>> 4GB swap partition is on a 4GB USB2 memory key (da1p1), everything else
>>>> is on the sdcard. There are no excessively long ms/w being recorded.
>>>> There are no USB or other related errors.
>>>> 
>>> 
>>> That's a little surprising, and disturbing. By my experience your setup
>>> should have run to completion.
>>> 
>>> Do you see a "too much swap" complaint? I don't know if it's a problem,
>>> but 4 GB of swap triggers one on my RPi3. 3 GB does not. 2 GB is enough
>>> to finish -j4 buildworld.
>> 
>> Jun 30 23:32:12 rpi3 kernel: pid 60735 (c++), uid 0, was killed: out of 
>> swap space
>> 
>> No go with 2GB (I deleted the da0p1 swap partition; destroyed da0; then 
>> remade it it with a 2GB p1; then rebooted - no "too much swap" 
>> complaints). Out of swap with 56M of 2GB used. And this was with make 
>> -j2 buildworld.
>> 
> It just crossed my mind that the successful -j4 buildworlds that used
> USB swap (both mechanical and flash) separate from /usr and /var placed
> the swap  on a powered USB hub.  It would be exceeding strange if that 
> proved helpful, but as things are going....

Power issues have been mentioned before in this exchange, but it can be
more like what one might notice with a oscilloscope than with a Digital
Multi-Meter. If the device sometimes (even very briefly) requires more
than the rpi3 provides (voltage or current) the device will likely
fail sometimes despite a DMM not showing anything interesting. The
same device might work fine on a powered hub that always provides
sufficient voltage and current (on all time scales involved).

I've had these sorts of situations before. Without a proper set of
instruments to monitor for power problems with, it is a pain to
figure out for sure if such is what is going on.

So I tend to use a powered hub for USB storage.


> The other successful -j4 buildworlds put swap on the root microSD card.
> I'd rate that a harder experiment, even if there is free space on the card.
> My talents with gpart leave much to be desired. If you're properly gifted
> it might also be worth trying.
> 
> . . .



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




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