Re: [Xen-devel] using mapped vcpu_runstate_info in hvm guest

[Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>]

On 20.11.2013 14:07, Jan Beulich wrote:
> > > > On 13.11.13 at 14:50, Juergen Gross <juergen.gross@xxxxxxxxxxxxxx> wrote:
> > I'm trying to obtain runstate information from the hypervisor in a hvm guest
> > via VCPUOP_register_runstate_memory_area. This works, but the information is
> > not completely suitable for a hvm guest:
> >
> > I can see the time summed up in the different states, but I'm not able to
> > deduce the exact time the current vcpu has been running. I see the time when
> > the last change to the running state happened (state_entry_time), but this
> > time is the hypervisor system time obtained via NOW(). I can't see how to
> > map this information to any time information available to the guest (e.g.
> > the tsc value).
> __update_vcpu_system_time() specifically considers the case of
> vTSC, so I'm not really clear what your problem here is. NOW()
> (and hence state_entry_time) are in ns units, and the information
> presented in struct vcpu_time_info should be sufficient to do the
> necessary mapping (or else I can't see what's different in your
> case from the usual PV or PVHVM one).
>
> > A solution would be to modify the runstate information mapped via
> > VCPUOP_register_runstate_memory_area: it could contain state_entry_time
> > rebased to the guests tsc.
> No, that one's defined to be matching up with vcpu_time_info's
> system_time.
Ah, okay. Then this was a mis-interpretation on my side.

Thanks for the info. :-)

I'll start another try based on this.


Juergen

--
Juergen Gross                 Principal Developer Operating Systems
PBG PDG ES&S SWE OS6                   Telephone: +49 (0) 89 62060 2932
Fujitsu                                   e-mail: juergen.gross@xxxxxxxxxxxxxx
Mies-van-der-Rohe-Str. 8                Internet: ts.fujitsu.com
D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel