Re: How to measure VM events using perf-event

[Tianwei Zhang <artdream07@gmail.com>]

In the KVM-based machine, each VM is a process, with several threads running concurrently. You can use ps -eLf to display all the VM threads. When measuring the performance of the VM, you should also specify the thread ids in the perf_event_open function. 

Tianwei

On Apr 10, 2015, at 12:17 PM, Jueyuan Zhu <jueyuan.zhu@gmail.com> 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
> 
> Thank you!
> 
> -Jueyuan
> 
> 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
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html