Re: [Qemu-devel] pert stat in KVM guest can not get LLC-loads hardware cache event

[Steven]

Hi, Kan,

The dTLB-load-misses is 0, but it shows 80.00%hit, does that mean the
TLB-load miss is 0.8 * (dTLB-loads). Thanks.

 Performance counter stats for './parsecmgmt -a run -i native -c
gcc-hooks -n 1 -p freqmine':


                 0 dTLB-load-misses          #    0.00% of all dTLB
cache hits  [80.00%]

   782,565,273,315 dTLB-loads
         [80.00%]

   782,552,911,616 L1-dcache-loads
         [80.00%]

     5,810,697,456 L1-dcache-load-misses     #    0.74% of all
L1-dcache hits   [80.00%]

     2,145,907,209 L1-dcache-prefetch-misses
         [80.00%]

- Hui

On Wed, Aug 27, 2014 at 9:05 AM, Liang, Kan <address@hidden> wrote:
>
>
>>
>> Dear KVM developers:
>> I am trying use perf stat inside a VM to obtain some hardware cache
>> performance counter values.
>> The perf stat can report some numbers for L1 and TLB related counters. But
>> for the LLC-loads and LLC-load-misses, the numbers are always 0. It seems
>> that the these offcore events are not exposed to the guest.
>>
>> Is this a bug in Qemu or KVM?
>>
>
> There is no offcore virtualization support in KVM yet.
> For you case, I guess you are using paravirt for guest, so it should be 0.
> Otherwise, you should get #GP in guest.
>
>
>> My testbed is
>>
>> Host kernel: 3.12.26
>> Qemu: 2.1.0
>> CPU: Intel Ivy bridge 2620
>> VM boosted by qemu, with -cpu host.
>>
>> Thanks.
>>
>> - Hui Kang