Re: [PATCH v5 0/3] Add support for the RAPL MSRs series

[Anthony Harivel]

Hi Daniel,

Daniel P. Berrangé, Apr 17, 2024 at 19:23:
> On Thu, Apr 11, 2024 at 02:14:31PM +0200, Anthony Harivel wrote:
> > Dear maintainers, 
> > 
> > First of all, thank you very much for your review of my patch 
> > [1].
> > 
> > In this version (v5), I have attempted to address all the problems 
> > addressed by Daniel during the last review. I've been more careful with 
> > all the remarks made.
>
> I'm wondering if you had tips for testing this functionality ?
>
> Is there any nice app to run in the host/guest to report the
> power usage, to see that it is working as desired ?
>

Great question. Unfortunately, there isn't an easy-to-use, 
out-of-the-box app that can assist you.

The 'cpupower' tool in linux/tools/power/ or 'turbostat' in 
linux/tools/power/x86/ require some modifications as they fail the 
sanity check inside a VM. It is on my agenda to work on a proposal patch 
for these tools if the vmsr patch lands in QEMU. These are the excellent 
apps that everyone should use IMO.

So how do I test my patch ? 
I'm using a slightly more complex tool called Kepler [1]. Since a patch 
that has been merged [2], it can also report VM consumption.
The installation is easy on RPM based distribution [3].
But indeed, this tools is a Prometheus exporter so you need 
a Prometheus/Grafana stack for the observation which make the test more 
complex than the 2 previous tools mentioned.

Last month, I conducted a test with Kepler tools on both a host and 
within VMs. I was pleased to observe that the power graph trends were 
identical both outside and inside the VMs, albeit with a slight 
variation in terms of 1:1 Watt comparison.

If Kepler isn't the tool you're looking for, I'm open to any suggestions 
regarding cpupower/turbostat. I can work on a temporary patch that would 
enable us to utilize them.

Regards,
Anthony

[1]: https://sustainable-computing.io/
[2]: https://github.com/sustainable-computing-io/kepler/pull/931
[3]: https://sustainable-computing.io/installation/kepler-rpm/