On Tue, 2012-07-24 at 18:15 +0200, Robert Richter wrote: > David, > > On 24.07.12 08:20:19, David Ahern wrote: > > On 7/23/12 12:13 PM, Arnaldo Carvalho de Melo wrote: > > > Em Fri, Jul 20, 2012 at 05:25:53PM -0600, David Ahern escreveu: > > >> PEBS cannot be used with guest mode. If user adds :p modifier set > > >> exclude_guest as well. > > > > > > Is this something Intel specific? Or can someone think of an arch where > > > this limitation wouldn't exist? > > > > Good point. So far precise_ip is used by arch/x86 only. I don't have an > > AMD based server so I don't know if there is a conflict between > > virtualization and IBS. Added Robert for advice. > > thanks for this hint. > > On AMD cpus precise_ip maps to IBS, which does not support hardware > options as perfctrs do. Thus, following attr flags are not supported: > > exclude_user, exclude_kernel, exclude_host, exclude_guest > > Counting in guest mode is possible with IBS, but not the exclusion of > a certain mode. If precise_ip counting is enabled on AMD we may not > set the exclude_guest flag.
IIRC we have SVM enter/exit hooks in kvm/perf already, we could use those to implement exclude_guest for IBS. Now I've been trying to find the patches that introduced that, but I'm failing horridly. Gleb, got us a pointer here? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
