[jfindley]

Memory de-dup is computationally expensive, and KSM hitrate is generally much worse than people tend to expect - not to mention that it comes with its own security issues. I agree that the security tradeoffs need to be taken seriously but the realworld performance/efficiency considerations are definitely not negligeable at scale.

There are also significant operational concerns. With containers you can just have your CI/CD system spit out a new signed image every N days and do fairly seamless A/B rollouts. With VMs that's a lot harder. You may be able to emulate some of this by building some sort of static microvm, but there's a LOT of complexity you'll need to handle (e.g. networking config, OS updates, debugging access) that is going to be some combination of flaky and hard to manage.

I by no means disagree with the security points but people are overstating the case for replacing containers with VMs in these replies.