[vbox-dev] Kernel Samepage Merging

James Lucas jimmy at secsme.org.au
Mon Nov 9 09:28:47 GMT 2009

I thought I would try something a little bit more complex for my next go at
delving into the VirtualBox source code however have become stuck and am hoping
that someone from Sun can give me a pointer in the right direction.

Kernel Samepage Merging has come to the linux kernel (Released in RHEL5.4 and
Fedora 12) and is utilised by KVM to perform memory overcommit for virtual
machines. Where exactly does VirtualBox allocate the VM memory structures? I
was finding code over the MM and PGM code but not exactly sure where the actual
allocation occurs.

I suspect that both the VirtualBox runtime and the host memory can be tagged as
mergeable. Host memory might be the best one to test out first (the code change
is trivial and advises the kernel that the memory is mergeable and request the
kernel to scan for identical pages)

I hope someone is able to help.

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