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

[Steven]

Inside the guest, I am using "perf stat -e dTLB-load-misses -e
dTLB-loads -e L1-dcache-loads -e L1-dcache-load-misses -e
L1-dcache-prefetch-misses  ", followed by the parsec command.

Thanks.

- Hui

On Wed, Aug 27, 2014 at 12:28 PM, Liang, Kan <address@hidden> wrote:
>
>> > 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':
>
> I'm not familiar with parsecmgmt. What’s the perf commands it calls?
>
>> >
>> >
>> >                  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