On Mon, 15 Jan 2018 22:03:19 -0800 (PST), Dannaz Perth
 declaimed the following:

>
>
>FYI. the Pi is only ever running Chromium and node-red.
>I have no other apps media programs and/or things running.
>I have team viewer installed but never actually fully opened.\
>
>https://pasteboard.co/H39bm5R.png
>
>Look forward to your advise

 Dump the browser?

 Your browser is eating >100% (being a four-core processor, 100% means
all of one core). Uh, and you seem to have two browser processes running
and between them they are eating a quarter of your memory (though that may
just mean Chromium runs a master process and an additional process per open
tab; I don't have the experience to tell).

 Using portions of multiple cores could be having an impact as each core
needs to flush/reload internal cache. Possibly locking the browser to
single core would help

http://xmodulo.com/run-program-process-specific-cpu-cores-linux.html

{Lock the browser process with the large %CPU value}

 Node-Red itself is not using much (though it is using a touch more than
the X-window system task). In truth -- at the time of that screen grab,
node-red is in a blocked/sleep state, doing nothing.

 On the summary (top part) you have no defined swap file (which is the
default configuration on both my RPI3 and BBB -- since if you really need
swap, you don't want it on an SD card [the HINT benchmark did kill my
original RPI3 SD card; I bought a USB-powered hard-drive to run a swap file
on]) -- but you have a quarter of RAM still free. Total CPU usage seems to
be about one third (remember -- four cores, so 25% is one core equivalent).

 The killer -- as I started -- is that you have ONE browser process that
is using more CPU than any single core can provide, hence resulting in
processor swapping, cache misses, and whatever locks are needed to ensure
one core isn't trying to read data that hasn't been written by another...
Note that the fourth active process is RCU_SCHED
https://www.kernel.org/doc/Documentation/RCU/whatisRCU.txt
which appears to be involved in maintaining data structures shared between
cores. {This is my first exposure to RCU}

 For comparison purposes (since you stated remoting in with the browser
running on another computer doesn't show the problem): set up the same run
as captured here, but do not run the browser locally. Use the remote
browser. Then capture the TOP output on the RPI again. Without the browser
hog on the RPI, I expect you'll see total CPU% down around 5-10%, or even
lower.
--
 Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

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