On Tue, May 12, 2026 at 15:13:58 +0200, Jedrzej Wasiukiewicz wrote:
> Linux kernel 7.0 introduced PERF_PKG_MON support in resctrl filesystem
> which exposes per-workload energy and performance monitoring.
> 
> This patch enables per-VM energy monitoring via core_energy (Joules) and
> activity (Farads) counters. Energy monitors can be configured through new
> <energytune> element under <cputune> following earlier cachetune and
> memorytune patterns.
> 
> Design notes:
> 
> Energy values from resctrl are floating-point. I added separate dvals/ndvals
> pair to virResctrlMonitorStats to handle them. I kept them in a single
> struct for easier integration with performance counters (integers and floats
> within same monitor) that might be integrated in another patch.
> 
> The new XML element is <energytune> under <cputune> following earlier pattern 
> for
> resctrl features (cachetune, memorytune). Energytune doesn't currently support
> the "tuning" part, only monitoring. I added it as energytune for consistency 
> with
> cache and memory features, keeping all resctrl handling under cputune. This 
> also makes
> sense with current resctrl architecture - all monitoring groups are part of an
> allocation group. This approach allows for easy opt-in/out on the monitoring 
> features.
> 
> Signed-off-by: Jedrzej Wasiukiewicz <[email protected]>
> Signed-off-by: Christopher M. Cantalupo <[email protected]>
> ---
> Please let me know if there's a better approach for this. I'm happy to rework
> the design based on feedback. I can also split this patch if necessary.



This patch will need to be split into multiple patches, as we usually
do.

> 
>  NEWS.rst                                      |   6 +

At the very least any change to NEWS.rst *must* be in a separate patch.

>  docs/formatdomain.rst                         |  20 ++
>  include/libvirt/libvirt-domain.h              |  65 +++++++
>  src/conf/capabilities.c                       |  42 ++++
>  src/conf/capabilities.h                       |   6 +
>  src/conf/domain_conf.c                        |  99 ++++++++++
>  src/conf/schemas/capability.rng               |  26 +++
>  src/conf/schemas/domaincommon.rng             |  19 ++
>  src/conf/virconftypes.h                       |   2 +
>  src/qemu/qemu_driver.c                        |  70 ++++++-
>  src/util/virresctrl.c                         | 180 +++++++++++++++---
>  src/util/virresctrl.h                         |  12 +-
>  .../genericxml2xmlindata/energytune-basic.xml |  32 ++++
>  tests/genericxml2xmltest.c                    |   1 +
>  14 files changed, 543 insertions(+), 37 deletions(-)
>  create mode 100644 tests/genericxml2xmlindata/energytune-basic.xml

[...]

Couple high-level points from scrolling through the overly-long patch:
 - some changes looked like cleanups mixed with implementation, try to
   separate cleanups as separate patches

 - separate out XML+schema+docs changes froma ctual implementation

 - separate out reporting (capabilities) from VM setup

 - ensure that everything can be compiled after every patch

 - avoid VIR_INFO and VIR_WARN as debug messages

> -- 
> 2.34.1
> 
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Funny to see such a disclaimer when posting stuff to public lists.

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