On 6/26/13 1:13 PM, Peipei Wang wrote:
Hi, all.
I got a new problem.
When I use perf to get CPI( cycles per instruction) on a Virtual
Machine, I receive the message that
cycles and instructions are not supported.
However, other events like page-faults or context-switches can be
supported well.
I don't know why. So I guess I can't user perf to record a certain
sort of performance events on Virtual Machine.
Is my guess correct?? What kind of performance events in hell aren't
supported?
KVM supports a virtual PMU which uses perf_events host side. I believe
it went into v3.2, so a host kernel version of 3.2 and greater will have it.
You also need an updated qemu version to set the cpuid bits. I forget
which version exactly - 1.2 should work.
David
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