Virtualizing hardware and running extra copies of the kernel has a small overhead. I'm not sure it matters for the majority of companies but it has a measurabl

Virtualizing hardware and running extra copies of the kernel has a small overhead. I'm not sure it matters for the majority of companies but it has a measurable impact for the gigantic ones. Afaik containization was rooted in the ability to run multi tenant servers without semi trusted apps overstepping their bounds. See Google Borg and Facebook Tupperware (iirc they started as chroot automation and expanded) Some stuff like Java have ran in a runtime level container long before OS containers so it seems a bit redundant there, but still facilities having conflicting versions of the runtime installed.