Re: Questing regarding KVM Guest PMU

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On Tue, Apr 3, 2012 at 10:28 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
> On Tue, Apr 03, 2012 at 07:20:04PM +0530, shashank rachamalla wrote:
>> On Mon, Mar 19, 2012 at 12:37 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
>> > On Mon, Mar 19, 2012 at 12:20:30PM +0530, shashank rachamalla wrote:
>> >> On Sun, Mar 18, 2012 at 10:21 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
>> >> > On Sun, Mar 18, 2012 at 09:47:55PM +0530, shashank rachamalla wrote:
>> >> >> >> I guess things are working fine with perf. But why not with oprofile ?
>> >> >> >>
>> >> >> > Looks like it. I never tried oprofile. Will try to reproduce your
>> >> >> > problem and see what oprofile is doing.
>> >> >>
>> >> >> I am using ubuntu 10.04 with 2.6.32-21-generic kernel as guest and
>> >> >> oprofile 0.9.6.
>> >> >> Also, I have tried to capture kvm-events ( perf patch ) in host while
>> >> >> running oprofile and perf in guest.
>> >> >> Please see the attachment. I have run the tests in three cases for the
>> >> >> around 5 secs.
>> >> >>
>> >> >> There are more number of MSR reads and writes in case of perf which I
>> >> >> think is normal. However, there are very few MSR reads and writes with
>> >> >> oprofile. Also, the number of NMI exceptions are too high in case of
>> >> >> oprofile.
>> >> >>
>> >> > Which host kernel are you using? Try latest kvm.git and check if you see
>> >> > something unusual in dmesg.
>> >>
>> >> Currenly running 3.3.0-rc5. will try with the latest source from kvm
>> >> git and let you know.
>> >>
>> >>
>> > Thanks, there were some fixes that didn't make it into 3.3. rdpmc
>> > instruction emulation fix is one of them. If oprofile uses it this can
>> > explain the problem.
>> >
>> I have tried with latest kvm source from git and also with 3.0 guest
>> kernel but oprofile fails to collect any samples on guest. I am using
>> a core2duo processor which is considered by oprofile as pentium pro
>> model.
>>
> core2duo on the host or the guest? What is your qemu command line?
>
both. qemu command line below.
sudo /usr/local/bin/qemu-system-x86_64 -drive
file=vdisk1.img,if=virtio -cpu host -m 2000 -net nic,model=virtio -net
user

> --
>                        Gleb.
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