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Moving the hypervisor off the main CPU has made Amazon more comfortable (from a security perspective) enabling "bare metal" features like hardware performance c
by khuey 6y ago
Moving the hypervisor off the main CPU has made Amazon more comfortable (from a security perspective) enabling "bare metal" features like hardware performance counters. Brendan Gregg has written quite a bit about how these are used at Netflix. We use them in rr[0] to enable fast recording of asynchronous events like signals and context switches.
Speaking of which, if anybody who works on EC2 is reading this it would be great if you could continue exposing more MSRs and bare metal features. rr in particular would like MSR_INTEL_MISC_FEATURES_ENABLES to be available[1], which would enable trace portability for traces recorded on EC2.
[0] https://github.com/mozilla/rr https://github.com/mozilla/rr
[1] https://github.com/mozilla/rr/issues/2667 https://github.com/mozilla/rr/issues/2667
- justicezyx 6y agoSeems hypervisor is still on main CPU: See figure 2 (2017 nitro architecture)
- _msw_ 6y agoDisclosure: I work at Amazon on building infrastructure for AWS For the bare metal instance configurations (where the instance size type in ".metal"), there is no hypervisor running on the processor.
- justicezyx 6y agoI cannot find docs sating nitro has any general purpose chip to run a hyper visor to manage the VMs, how customer vm get launched and managed from outside the physical host?
- _msw_ 6y agoThe management of the physical host itself (including launching and terminating customer instances when running in bare metal mode) is the responsibility of a component of our server called the Nitro controller.