[dm-devel] Shared Memory Pages for Same Base Device

[Shao Miller]

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/
-- 

Shao Miller
/Network Technician/
/905-836-4442 *ext: 112*/
www.treefrog.ca/shao-miller <http://www.treefrog.ca/shao-miller>
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