We've had various mechanisms for this and some of them have even been deprecated. Transparent Page Sharing was deprecated in VMware as it turned out to not be s

We've had various mechanisms for this and some of them have even been deprecated. Transparent Page Sharing was deprecated in VMware as it turned out to not be super useful in large pages. We have Kernel Same-Page Merging but many folks are disabling this in a post-Meltdown/post-Spectre world as the potential vulnerabilities aren't worth it.