https://community.intel.com/t5/Software-Tuning-Performance/PEBS-for-KVM-guest/m-p/1150626#M6817 <P>I was looking into the perf code to enable PEBS sampling for KVM guest. While registering perf_event_attr, I have set exclude_guest = 0 and exclude_host = 1. With this setting I am not receiving any PEBS samples.</P> <P>After digging into the kernel code, I have found that, in <STRONG><EM>add_atomic_switch_msr</EM></STRONG> function, <STRONG>MSR_IA32_PEBS_ENABLE</STRONG> is being set to 0.</P> <P>It also states that, "PEBS needs a quiescent period after being disabled (to write a record).&nbsp; Disabling PEBS through VMX MSR swapping doesn't provide that period, so a CPU could write host's record into guest's memory."</P> <P>Is it possible to enable the PEBS for guest while keeping the host PEBS disabled?</P> <P>&nbsp;</P> <P>&nbsp;</P> Tue, 03 Jul 2018 16:18:42 GMT proy4 2018-07-03T16:18:42Z https://community.intel.com/t5/Software-Tuning-Performance/PEBS-for-KVM-guest/m-p/1150626#M6817 <P>I was looking into the perf code to enable PEBS sampling for KVM guest. While registering perf_event_attr, I have set exclude_guest = 0 and exclude_host = 1. With this setting I am not receiving any PEBS samples.</P> <P>After digging into the kernel code, I have found that, in <STRONG><EM>add_atomic_switch_msr</EM></STRONG> function, <STRONG>MSR_IA32_PEBS_ENABLE</STRONG> is being set to 0.</P> <P>It also states that, "PEBS needs a quiescent period after being disabled (to write a record).&nbsp; Disabling PEBS through VMX MSR swapping doesn't provide that period, so a CPU could write host's record into guest's memory."</P> <P>Is it possible to enable the PEBS for guest while keeping the host PEBS disabled?</P> <P>&nbsp;</P> <P>&nbsp;</P> Tue, 03 Jul 2018 16:18:42 GMT https://community.intel.com/t5/Software-Tuning-Performance/PEBS-for-KVM-guest/m-p/1150626#M6817 proy4 2018-07-03T16:18:42Z