Em Wed, Feb 15, 2017 at 03:05:10PM +0200, Alexander Shishkin escreveu: > Peter Zijlstra <pet...@infradead.org> writes: > > > On Wed, Feb 15, 2017 at 10:34:58AM +0200, Alexander Shishkin wrote: > > > >> Well, we can't make the limitation go away. You'll still have to stop > >> kvms to get any 'meaningful' PT data. > > > > Why would you need to stop all VMs in order to get your !VM data? Sure, > > you get black holes where the VM runs, but we should be able to see > > everything else. > > No, what I mean is that if you run kvm prior to starting perf record, > which I assume is the case for acme, your entire session is a black
Exactly. > hole. The VMXON happens pretty early on, you can open /dev/kvm, > ioctl(KVM_CREATE_VM) on it and that will do a VMXON already. > > The problem is that PT (on BDW) doesn't trace inside VM root mode, not > just between VM entry/VM exit. Which is just unfortunate, destroys PT for a rather common use case :-\ Guess I need a <fill in the broadwell successor that allows using PT together with VMs> Which is? :-) - Arnaldo
