On Fri, Nov 29, 2013 at 8:16 PM, Vince Weaver <vi...@deater.net> wrote: > On Thu, 28 Nov 2013, Stephane Eranian wrote: > >> On Thu, Nov 28, 2013 at 1:26 PM, Ingo Molnar <mi...@kernel.org> wrote: >> > >> > * Vince Weaver <vi...@deater.net> wrote: >> > >> >> On Wed, 27 Nov 2013, Stephane Eranian wrote: >> >> >> >> > On Wed, Nov 27, 2013 at 7:35 PM, Vince Weaver <vi...@deater.net> wrote: >> >> >> >> > > So I notice PP1 (which is the GPU power on non-server chips) >> >> > > is not supported. >> >> > > >> >> > > Is that just for simplicity? >> >> > > >> >> > Does it work on specific models only? I bet so. How to detect those? >> >> >> >> In general it is on the machines that don't support the DRAM measurements >> >> (so the non-EP machines) but I don't know if there's a nice list anywhere. >> >> >> >> Intel manuals say: >> >> For a client platform, PP1 domain refers to the power plane of a >> >> specific device in the uncore. For server platforms, PP1 domain is not >> >> supported, >> >> >> >> usually PP1 I think maps to the embedded GPU. >> > >> > It would indeed be nice to expose PP1 too via the same facility - >> > Haswell and later spends some 40% of the CPU die on the integrated GPU >> > and people end up using it. >> > >> My worry is to determine if the GPU is actually enabled or even present. >> Using the x86_model may not be enough for that. > > In my experience if the device is not there you just get 0s as results > from RAPL (I've also seen this on some Sandybridge-EP machines we have > that for whatever reason don't support the DRAM RAPL results). > > So in theory it would be harmless to export the values even if not > supported. What is the worst failure mode? That somehow a recent CPU > doesn't support the MSR and we get a GPF when trying to access it? > Yes. I think that's what you get with DRAM on client for instance.
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