Welcome to post 46 in the $R^4 series!
r2u, introduced less
than three years ago in post
#37, has become a runaway success. When I last tabulated downloads
in early January, we were already at 33 million downloads of binary CRAN packages across the three
Ubuntu LTS releases we support. These were exclusively for the ‘amd64’
platform of standard (Intel or AMD made) x64_64 cpus. Now we are happy
to announce that arm64 support has been added and is available!
Why arm64?
The arm64 platform is already popular on (cloud) servers and is being
pushed quite actively by the cloud vendors. AWS calls their cpu
‘graviton’, GCS calls it ‘axion’. General servers call the cpu ‘ampere’;
on laptop / desktops it is branded ‘snapdragon’ or ‘cortex’ or something
else. Apple calls their variant M1, M2, … up to M4 by now (and Linux
support exists for the brave, it is less straightforward). What these
have in common is a generally more favourable ‘power consumed to ops
provided’ ratio. That makes these cheaper to run or rent on cloud
providers. And in laptops they tend to last longer on a single charge
too.
Distributions such as Debian, Ubuntu, Fedora had arm64 for many
years. In fact, the CRAN
binaries of R, being made as builds at launchpad.net long provided arm64 in
Michael’s repo, we now also mirror these to CRAN. Similarly, Docker has long
supported containers. And last but not least two issue tickets (#40, #55) had asked
a while back.
So Why Now?
Good question. I still do not own any hardware with it, and I have
not (yet?) bothered with the qemu-based emulation layer. The real
difference maker was the recent availability of GitHub Actions instances
of ‘ubuntu-24.04-arm’ (and now apparently also for 22.04).
So I started some simple experiments … which made it clear this was
viable.
What Does It Mean for a CRAN
Repo?
Great question. As is commonly known, of the (currently) 22.1k CRAN
packages, a little under 5k are ‘compiled’. Why does this matter?
Because the Linux distributions know what they are doing. The 17k (give
or take) packages that do not contain compiled code can be used as is
(!!) on another platform. Debian and Ubuntu call these builds ‘binary:
all’ as they work all platforms ‘as is’. The others go by ‘binary: any’
and will work on ‘any’ platform for which they have been built. So we
are looking at roughly 5k new binaries.
So How Many Are There?
As I write this in early March, roughly 4.5k of the 5k. Plus the
17.1k ‘binary: all’ and we are looking at near complete coverage!
So What Is The Current State?
Pretty complete. Compare to the amd64 side of things, we do not (yet
?) have BioConductor support; this may be added. A handful of packages
do not compile because their builds seem to assume ‘Linux so must be
amd64’ and fail over cpu instructions. Similarly, a few packages want to
download binary build blobs (my own Rblpapi among them) but
none exist for arm64. Such is life. We will try to fix builds as time
permits and report build issues to the respective upstream repos. Help
in that endeavour would be most welcome.
But all the big and slow compiles one may care about (hello
duckdb, hello arrow, …) are there. Which is
pretty exciting!
How Does One Get Started?
In GitHub Actions, just pick ubuntu-24.04-arm as the
platform, and use the r-ci or r2u-setup
actiions. A first test yaml exists
worked (though this last version had the arm64 runner commented out
again). (And no, arm64 was not faster than amd64. More tests
needed.)
For simple tests, Docker. The rocker/r-ubuntu:24.04
container exists for arm64 (see here), and one
can add r2u support as is done in
this Dockerfile which is used by the builds and available as
eddelbuettel/r2u_build:noble. I will add the standard
rocker/r2u:24.04 container (or equally
rocker/r2u:noble) in a day or two, I had not realised I
wasn’t making them for arm64.
One a real machine such as a cloud instance or a proper instance,
just use the standard r2u script for noble aka 24.04
available here.
The key lines are the two lines
echo "deb [arch=amd64,arm64] https://r2u.stat.illinois.edu/ubuntu noble main" \
> /etc/apt/sources.list.d/cranapt.list
# ...
echo "deb [arch=amd64,arm64] https://cloud.r-project.org/bin/linux/ubuntu noble-cran40/" \
> /etc/apt/sources.list.d/cran_r.list
creating the apt entry and which are now arm64-aware.
After that, apt works as usual, and of course r2u works as
usual thanks also to bspm so you can just do, say
install.packages(c("tidyverse", "brms", "rstan", "sf", "terra"))
and enjoy the binaries rolling in. So give it a whirl if you have
access to such hardware. We look forward to feedback, suggestes, feature
requests or bug reports. Let us know how it goes!
This post by Dirk
Eddelbuettel originated on his Thinking inside the box
blog. If you like this or other open-source work I do, you can now sponsor me at
GitHub.
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