Tracing KVM with Systemtap

[Rayson Ho <rho@redhat.com>]

Hi all,

I am a developer of Systemtap. I am looking into tracing KVM (the kernel
part and QEMU) and also the KVM guests with Systemtap. I googled and
found references to Xenprobes and xdt+dtrace, and I was wondering if
someone is working on the dynamic tracing interface for KVM?

I've read the KVM kernel code and I think some expensive operations
(things that need to be trapped back to the host kernel - eg. loading of
control registers on x86/x64) can be interesting spots for adding an SDT
(static marker), and I/O operations performed for the guests can be
useful information to collect.

I know that KVM guests run like a userspace process and thus techniques
for tracing Xen might be overkilled, and also gdb can be used to trace
KVM guests. However, are that anything special I need to be aware of
before I go further into the development of the Systemtap KVM probes?

(Opinions / Suggestions / Criticisms welcome!)

Thanks,
Rayson