Raspberry Pi 2 as my main desktop

Raspberry Pi 2 as my main desktop
=================================
2015-09-02

A couple of weeks ago I started using a Raspberry Pi 2 as my
main desktop. It was an experiment, suggested by some folks
on the #aardvark channel at irc.cnaude.org, and to
my amazement it works great. I rarely have to boot my
monster PC since, saving a lot on my power bills and
finding new ways of increasing my productivity by using
lighter apps at the same time. In this blog post I will
describe my current hardware and software setup and
give some tips on overclocking this single board
computer.

Hardware
--------
The Rpi 2 is a neat little board with 1GB of Ram and a
900MHz quad core ARM Cortex A-7 CPU. It is connected to my
router through the on-board ethernet port and I have
attached an external 3.5" HDD case which houses a relatively
slow Crucial BX 100 250GB SSD. I chose to use a 3.5" case,
since it has its own power supply. Most 2.5" cases out
there take their power straight from the USB port, but since
the Pi hasn't got power in abundance, I thought this would
be the smarter choice. Since I'm connecting the SSD through
a slow USB2 port I could have also gone with a regular HDD
without loss of performance, but I kind of like the silence
and lower energy consumption of the SSD.

The Pi get's its juice from a 2.1 Ampere iPad adapter that
came with the first iPad. I have used the shortest USB cable
I could find, to make sure all the juice gets to the board
without too much loss. You really want at least 2 amps to
power your Pi, because you're probably attaching a bunch of
USB peripherals, and you might want to overclock. You can
find out that your Pi doesn't have enough power when the
"rainbow square" on the top right of your screen appears.

To enable my overclocking endeavors I have bought a small
copper heat-sink, and attached it to the CPU. The Pi case I
got has small air holes on the top and enough room inside to
accommodate the CPU heat-sink.

Overclocking
------------
I have moderately overclocked my Pi. I used Hayden James'
excellent tutorial [1] on this subject. It appears that
there's no silver bullet though, because the build quality
varies from Pi to Pi, so you'll just have to test and figure
out yourself. It's best to start conservatively and work
your way up. A good way to maximize the load of your CPU and
RAM is by installing 'stress' and running this commands:

$ stress -c 4 --vm-bytes $(awk '/MemFree/{printf "%d\n", $2
* 0.9;}' < /proc/meminfo)k --vm-keep -m 1

This will stress test all your cores and RAM. While doing
this you can monitor the system temperature with:

$ vcgencmd measure_temp

You can overclock the Pi by modifying /boot/config.txt. My
current setup:

arm_freq=1000
sdram_freq=450
core_freq=450
over_voltage=8
force_turbo=1

This configuration will void your warranty because I have
enabled force_turbo, to make sure that the scaling governor
won't throttle down when the Pi is at rest. I don't mind
that it throttles by default, but there's this little lag
that's especially annoying when you load a web page. The
governor usually throttles just after the site is loaded,
making it less useful.

I managed to run the CPU at 1250MHz and both the SDRAM and
core at 550, but this wasn't too stable when working on the
Pi for the entire day. You don't want to overclock the RAM
too much, since the chip's specification shows that it was
designed to run at 400MHz. All in all I think that forcing
turbo is the biggest benefit here.

With these settings my Pi runs perfectly stable and rarely
gets hotter than 50 degrees celsius.

Software
--------
I installed vanilla Raspbian on my Pi using the NOOBS
network installer from the main Raspberry Pi website. I
quickly swapped the default desktop for xmonad, because it's
a lot lighter (and I'm a big Haskell fan-girl). I realized I
needed to change some of my computing habits, so I switched
to Mutt for e-mail and Newsbeuter for all my RSS-feeds.

When you start using the Pi full-time you will get a keen
eye on how demanding all the processes are and one thing
that will immediately jump at you is how poorly most
browsers perform. This is the reason why the Raspberry Pi
Foundation made modifications to Epiphany to make it a bit
more snappy. But still, you would like to avoid
javascript-heavy websites like youtube.com and you'll get
adept at finding alternatives: Youtube-dl for downloading
youtube videos for example.

I tried porting Fennec (Mozilla Mobile) to the Pi, since
this ARM-browser runs great on my cheap Android tablet.
However, Mozilla seems to have switched their focus for
Fennec to Android, so I had to rollback 100k of Mercurial
commits to get to a version that still had Linux Desktop
support. Long story cut short: I couldn't get it to compile
and didn't want to make it a knight's quest getting it to
run. Instead I switched to using Dillo for quickly looking
up things and I'm using Epiphany and Chromium for web
development. Chromium suffices nicely for debugging the web
apps I built for my work and after I overclocked I'm
actually quite happy with its performance.

It's a bit odd that browsers don't run faster, since
browsing works fine on cheap ARM-based tablets. I guess
those have a lot of special ARM-optimizations, and it also
helps that they are more closely tight to the GPU for
displaying the latest CSS3 transforms and Javascript-based
trickery. It would really be nice if someone ported the
Android webview, or Fennec to the Pi, utilizing OpenGL ES
directly for rendering.

Speaking of OpenGL, you will notice that some games in the
default Raspbian repo run extremely slow. This is because
they have been written for the regular OpenGL and need to be
ported to OpenGL ES for acceleration. There are a couple
projects that can help you porting, without having to
overhaul the entire graphics stack. Check out Regal [2] and
GLShim [3] if you're interested.

I'm trying to port Armagetron to the Pi, because I have a
tron server daemon running on my VPS and would love to
continue playing it. That aside, there's a lot of fun and
play to be had on the Pi. There are many emulators
available, and I recommend using Retropie to install
standalone versions of the available emulators. Especially
Retroarch is pretty neat.

Quake 1 to 3 also run great on the Pi, as does Dosbox, so
there's more than enough out there for your leisurely Pi
usage. Personally I tend to avoid the official Pi store for
software, since it seems to be ridden with GPL-violating
packages.

Software freedom is actually the one thing that bugs me
about the Pi. Its firmware and drivers aren't all free and
open source and although you can decide for yourself how
long your freedom beard grows about this subject, it doesn't
help the Linux and BSD support for the Pi. Personally I
would love to run NetBSD on this machine, but without
hardware accelerated graphics I don't see the point. If
freedom is really important to you, you might want to wait
for the 9 dollar chip by Next Thing Co.

One thing that amazed me is that Libreoffice runs way better
than Abiword. I quite expected the opposite and don't know
whether this is something that's caused by my specific
setup, but Libreoffice runs nice and snappy. Anyway, since
my pc-swap fired up the minimizer in me, I'm considering
moving all my Libreoffice templates to LaTeX instead.

Conclusion
----------
The Pi is a nifty bit of kit and more than powerful enough
to replace my desktop for most of my computing. Critics
regard it as a mere toy, but it's quite powerful at that.
Fine-tuning the Pi, and finding new and better apps that
replace the bloated ones you were using is pretty sweet and
good for your productivity. I intend to keep using the Pi
for most of my work and hope to someday update it to a 8GB
octacore Pi 3.

Hyperlinks:
[1]: http://haydenjames.io/raspberry-pi-2-overclock/
[2]: https://github.com/p3/regal
[3]: https://github.com/lunixbochs/glshim

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Tags: english