On 06/10/2010 08:44 AM, Jes Sorensen wrote:
On 06/08/10 20:43, Gordan Bobic wrote:
Is this plausible?
I'm trying to work out if it's even worth considering this approach to
enable all memory used by in a system to be open to KSM page merging,
rather than only memory used by specific programs aware of it (e.g.
kvm/qemu).
Something like this would address the fact that container based
virtualization (OpenVZ, VServer, LXC) cannot benefit from KSM.
What I'm thinking about is somehow intercepting malloc() and wrapping it
so that all malloc()-ed memory gets madvise()-d as well.
Not sure if it is worth it, but you might want to look at ElectricFence
which does malloc wrapping in a somewhat similar way. It might save you
some code :)
I'll look into it, but I don't see this requiring more than maybe 50
lines of code, including comments, headers and Makefile. I was planning
to literally just intercept mmap()/brk()/malloc() and mark them with
madvise() when the underlying call returns.
Which brings me to another question:
Would intercepting malloc() be completely redundant if mmap() is
intercepted? Would I also need to do something with intercepting free()?
Is three anything else I would need to intercept?
Whether or not you will run into problems if you run it system wise is
really hard to predict. Any other application that might be linked in a
special way or use preload itself might bark, but you can try it out and
see what explodes.
Thanks for the heads up. Can you think of any such applications off the
top of your head?
Gordan
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