Messages in this thread |  | | From | Andi Kleen <> | Subject | Re: [Feature] x86_64 page tracking for Stratus servers | Date | Wed, 6 Sep 2006 09:36:19 +0200 |
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> Silly question, why can't you do all this from stop_machine_run context (or > your SMI) that doesn't have to worry about other CPUs dirtying memory?
Because that would be too slow for continuous mirroring.
You can't go through 10+GB of virtual memory (or more with shared memory because the scan has to be virtual) in an interrupt.
The only sane way is to do it continuously.
> [*] Though if it gets included, it would not stop me lamenting the > proliferation of complexities to support *tiny* obscure userbases. Can > we wait until your hardware is smart enough to snoop the cc? :)
My guess is that if we had a generic memory mirror subsystem other people would find uses for it too. e.g. a lot of systems support spare DIMMs these days and mirroring some memory to it seems like a smart idea. That means normally the hardware does it, but perhaps some stuff can be done better by doing it in software.
Or it is also a bit similar to the algorithms Xen uses for live migration. If that was implemented on the kernel level something like this might be useful too. I think OpenVZ has some kind of migration support, but it's currently not live.
-andi
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