Re: How to measure VM events using perf-event

[Christopher Covington <cov@codeaurora.org>]

Hi Jueyuan,

On 04/10/2015 12:17 PM, Jueyuan Zhu wrote:
> Hi Chris,
> 
> Thanks for your suggestions. Since I am using the perf_event_open in the
> host OS, not in the guest OS. So does it need the support of PMU
> virtualization? I used the perf command below to measure the VM, and it can
> give correct results. So I am wondering how to use perf_event_open to get the
> same results as the perf user command?
> 
> #perf stat -e instructions -p VM_id sleep 1

Sorry, I overlooked that. I like to set pinned and inherit, but nothing jumps
out to me as wrong. If you'd like to look at more examples of using
perf_event_open, the test suite has the largest collection I know of.

https://github.com/deater/perf_event_tests

Chris

> On Apr 10, 2015, at 11:39 AM, Christopher Covington <cov@codeaurora.org> wrote:
> 
>> Hi Jueyuan,
>>
>> On 04/09/2015 11:46 PM, Jueyuan Zhu wrote:
>>> Hello,
>>>
>>> I am trying to use the perf-event to measure the events for one specified
>>> VM in KVM platform. Since each VM is just a process in the host OS, so I thought
>>> we could just set the process id of this VM in the perf-event_open API to
>>> count the events. The following is my code (based on the example from
>>> perf_event_open linux manual). 
>>
>>> However, this program’s output keeps constant whenever this VM is idle, or
>>> running different benchmarks. So it seems the event counting is incorrect. Can
>>> anyone tell me how to set the flags or perf_event_attr to correctly count the
>>> VM events using perf_event_open? 
>>
>> You may want to check that the QEMU or kvmtool you're using correctly
>> virtualizes or emulates the PMU for your architecture. Information about this
>> might be in the documentation or release notes or if not you could try asking
>> on the QEMU or kvmtool mailing list tool.
>>
>> Chris
>>
>> -- 
>> Qualcomm Innovation Center, Inc.
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>> a Linux Foundation Collaborative Project
> 
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-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project