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apple / swift-nio

Event-driven network application framework for high performance protocol servers & clients, non-blocking.
https://swiftpackageindex.com/apple/swift-nio/documentation
Apache License 2.0
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Building SwiftNIO on ARM in a docker takes a very long time compared to AMD builds #1880

Closed hendesi closed 3 years ago

hendesi commented 3 years ago

First of all, I want to say a huge thank you. This is a framework I've been using for a while now and its just awesome. You guys have been doing an amazing job!

To my problem: When building a simple swift package that has only swift-nio as a dependency on docker, the build times are highly different for ARM and AMD architectures. The docker step RUN swift build -j 1 -c release -v took around 300 seconds on AMD and on ARM It takes 2335 s, so almost 40 minutes just for building this package. This is a huge difference.

Expected behavior

I'm not an expert on this, but I would expect the build times on arm and amd architectures to be somewhat similar.

Actual behavior

The actual build times for the different platforms differ significantly.

Steps to reproduce

  1. Clone this repository
  2. cd SwiftNIODemoProject
  3. Run docker buildx build --platform linux/arm64 -f DockerfileArm -t test-swiftnio-arm .
  4. Run docker buildx build --platform linux/amd64 -f DockerfileAmd -t test-swiftnio-arm .
  5. Compare build times.

SwiftNIO version/commit hash

Swift & OS version (output of swift --version && uname -a)

swift --version

Swift 5.5 Development Trunk Base for the AMD build is the official swiftlang/swift:nightly-5.5-focal image Since the official image is AMD only, the base image for ARM builds was created by this dockerfile using the official tar.

uname -a

Darwin Felixs-MBP 20.3.0 Darwin Kernel Version 20.3.0: Thu Jan 21 00:07:06 PST 2021; root:xnu-7195.81.3~1/RELEASE_X86_64 x86_64

Do you know there cause of this or if there are any flags that one can use to speed things up on ARM?

Lukasa commented 3 years ago

Are you building natively on ARM64? What ARM64 CPU are you using?

Lukasa commented 3 years ago

Ah, never mind, I see you're using docker buildx.

docker buildx runs your build under virtualisation using QEMU when you build for non-native architectures. As your machine is an Intel-based machine, this means you have to virtualise when building for AMD64. This is software virtualisation using Qemu, so sadly it's fairly slow. There isn't much we can do about that directly: this is a CPU-bound problem.