Good day to all.
If I've some block device "base" and I've two derived device-mapper
devices "derived1" and "derived2" that are copy-on-write layers over
top of that base, and I mount the filesystems on those derived block
devices and run the same program "foo" from both, does the "foo"
running from "derived1" share any [read and execute] memory pages
with the "foo" running from "derived2", since the underlying sectors
are both from the same position on "base"?
The more general question would be about mmap, but I hope this
example is clear. "Docker"[1] uses device-mapper in scenarios like
the above example and I'm curious if they benefit from shared pages.
[1] https://www.docker.com/