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SubjectRe: [RFC][PATCH] KVM: perf: a smart tool to analyse kvm events
On 01/16/2012 11:30 AM, Xiao Guangrong wrote:
> This tool is very like xenoprof(if i remember correctly), and traces kvm events
> smartly. currently, it supports vmexit/mmio/ioport events.
>
> Usage:
> - to trace kvm events:
> # ./perf kvm-events record
>
> - show the result
> # ./perf kvm-events report
>
> Some output are as follow:
> # ./perf kvm-events report
> Warning: Error: expected type 5 but read 4
> Warning: Error: expected type 5 but read 0
> Warning: unknown op '}'
>
>
> Analyze events for all VCPUs:
>
> VM-EXIT Samples Samples% Time% Avg time
>
> APIC_ACCESS 438107 44.89% 6.20% 17.91us
> EXTERNAL_INTERRUPT 219226 22.46% 8.01% 46.20us
> IO_INSTRUCTION 122651 12.57% 1.88% 19.44us
> EPT_VIOLATION 83110 8.52% 1.36% 20.75us
> PENDING_INTERRUPT 37055 3.80% 0.16% 5.38us
> CPUID 32718 3.35% 0.08% 3.15us
> EXCEPTION_NMI 23601 2.42% 0.17% 8.87us
> HLT 15424 1.58% 82.12% 6735.06us
> CR_ACCESS 4089 0.42% 0.02% 6.08us
>
> Total Samples:975981, Total events handled time:126502464.88us.

Nice! If we can have a live version as well, this can replace kvm_stat.

The average numbers are really high. Like a factor of 3x-4x off. Would
be good to print the standard deviation and see why. Maybe it's due to
the tracing overhead.

> The default event to be analysed is vmexit, we can use --event to specify it,
> for example, if we want to trace mmio event:
> # ./perf kvm-events report --event mmio
> Warning: Error: expected type 5 but read 4
> Warning: Error: expected type 5 but read 0
> Warning: unknown op '}'
>
>
> Analyze events for all VCPUs:
>
> MMIO Access Samples Samples% Time% Avg time
>
> 0xfee00380:W 196589 64.95% 70.01% 3.83us
> 0xfee00310:W 35356 11.68% 6.48% 1.97us
> 0xfee00300:W 35356 11.68% 16.37% 4.97us
> 0xfee00300:R 35356 11.68% 7.14% 2.17us

These are more reasonable (though still high - 5us for an ICR write?)

>
> Total Samples:302657, Total events handled time:1074746.01us.
>
> We can use --vcpu to specify which vcpu is traced:
> root@localhost perf]# ./perf kvm-events report --event mmio --vcpu 1
> Warning: Error: expected type 5 but read 4
> Warning: Error: expected type 5 but read 0
> Warning: unknown op '}'
>
>
> Analyze events for VCPU 1:
>
> MMIO Access Samples Samples% Time% Avg time
>
> 0xfee00380:W 58041 71.20% 74.90% 3.70us
> 0xfee00310:W 7826 9.60% 5.28% 1.93us
> 0xfee00300:W 7826 9.60% 13.82% 5.06us
> 0xfee00300:R 7826 9.60% 6.01% 2.20us
>
> Total Samples:81519, Total events handled time:286577.81us.
>
> And, '--key' is used to sort the result, the possible value sample (default,
> the result is sorted by samples number), time(the result is sorted by time%):
> # ./perf kvm-events report --key time
> Warning: Error: expected type 5 but read 4
> Warning: Error: expected type 5 but read 0
> Warning: unknown op '}'
>
>
> Analyze events for all VCPUs:
>
> VM-EXIT Samples Samples% Time% Avg time
>
> HLT 15424 1.58% 82.12% 6735.06us
> EXTERNAL_INTERRUPT 219226 22.46% 8.01% 46.20us
> APIC_ACCESS 438107 44.89% 6.20% 17.91us
> IO_INSTRUCTION 122651 12.57% 1.88% 19.44us
> EPT_VIOLATION 83110 8.52% 1.36% 20.75us
> EXCEPTION_NMI 23601 2.42% 0.17% 8.87us
> PENDING_INTERRUPT 37055 3.80% 0.16% 5.38us
> CPUID 32718 3.35% 0.08% 3.15us
> CR_ACCESS 4089 0.42% 0.02% 6.08us
>
> Total Samples:975981, Total events handled time:126502464.88us.
>
> I hope guys will like it and any comments are welcome! :)

I think it's great! A live version would be a nice addition too.

Please copy the perf userspace maintainers to get more detailed review
in the next version.

--
error compiling committee.c: too many arguments to function



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