Hacker News Reader

Comment by bradgessler | Hacker News Reader

I'm curious why file system performance from the VM through the hypervisor to the host is so slow on macOS. Is this some sort of fundamental limitation or is it a case of "Apple hasn't made this a priority"?

My knowledge could be out of date and maybe this is fixed, but I've tried using Docker on macOS and it's almost unusable for dev environments with lots of files because of the file system performance.

View on HN

How recently have you tried it? The current best-performance option for bind mounts in Docker Desktop on macOS (VirtioFS, using Hypervisor.framework) didn't become the default until June (for new installs) or September (for existing installs), and wasn't available at all prior to December 2022.

I haven't tried it on a large project recently. How good is it?

Better, but still a pain. Nothing compared to running Docker on Linux.

But docker on Linux doesn't involve any virtualization whatsoever so filesystem performance is 100% native

Have you tried OrbStack?

Cross-OS fs performance is a problem, especially latency wise. It’s the same with parallels, virtualbox, vmware, across just any fs. Or, you can have problems with hardlinks as well.

I personally use mutagen to sync host and vm and it works great.

Did you have VirtioFS enabled when you tried it?

File performance in itself isn’t bad per se, but keeping two file trees in sync is a mess with Docker because every file operation needs to be duplicated or something. There’s some async stuff as well but ultimately most programs meant for Linux assume file access to be super fast so any sort of intermediate steps end up being slow (see also: git on Windows being dog slow)

You want super speedy docker on Mac? Run docker _inside_ a Linux vm. Even better, just use Linux!

Reply on news.ycombinator.com