Re: [PATCH v32 0/5]Timestamp synchronization of host - guest tracing session

[Stefano De Venuto <stefano.devenuto99@gmail.com>]

On 3/19/21 12:55 PM, Tzvetomir Stoyanov wrote:
> Hi Stefano,
>
> On Fri, Mar 19, 2021 at 12:08 PM Stefano De Venuto
> <stefano.devenuto99@gmail.com> wrote:
Hi!
>> The commands used to record are:
>>
>> Host:
>> # trace-cmd record -C x86-tsc -e kvm:* -e msr:* -A tumbleweed:823 -e
>> msr:* -C x86-tsc sleep 1
> The guest trace clock is set automatically as the host, so this
> command should be enough:
> # trace-cmd record -C x86-tsc -e kvm:* -e msr:* -A tumbleweed:823 -e
> msr:*  sleep 1
>
>> Guest:
>> # echo x86-tsc > /sys/kernel/tracing/trace_clock
> There is no need to set manually the guest clock, it will be
> overwritten by trace-cmd agent.
>
Thanks so much for the proper way to do it, really appreciated.
>> If necessary, I can provide more info about my setup, or do more tests.
> Yes, please can you send me both host and guest trace files ?
Here are the trace files, host and guest respectively:

- http://xenbits.xen.org/people/dariof/tracing-examples/kvm/sync-kvmclock/trace.dat
- http://xenbits.xen.org/people/dariof/tracing-examples/kvm/sync-kvmclock/trace-tumbleweed.dat

> Also, it will be useful to send me the content of the KVM debug files:
>     /sys/kernel/debug/kvm/<guest ID>/vcpu<*>/tsc-offset
The guest has one vcpu (vcpu0) and the content of the file is:

255647917761327
>>
>> Thanks and Regards,
>>
>> Stefano
> Thanks for testing this code!
>
Thanks for your time,

Stefano