Re: [PATCH v8 0/4] KVM statistics data fd-based binary interface

Paolo Bonzini
2021-06-11T13:35:05Z

On 11/06/21 14:46, Jing Zhang wrote:
> This patchset provides a file descriptor for every VM and VCPU to read
> KVM statistics data in binary format.
> It is meant to provide a lightweight, flexible, scalable and efficient
> lock-free solution for user space telemetry applications to pull the
> statistics data periodically for large scale systems. The pulling
> frequency could be as high as a few times per second.
> In this patchset, every statistics data are treated to have some
> attributes as below:
> * architecture dependent or generic
> * VM statistics data or VCPU statistics data
> * type: cumulative, instantaneous,
> * unit: none for simple counter, nanosecond, microsecond,
> millisecond, second, Byte, KiByte, MiByte, GiByte. Clock Cycles
> Since no lock/synchronization is used, the consistency between all
> the statistics data is not guaranteed. That means not all statistics
> data are read out at the exact same time, since the statistics date
> are still being updated by KVM subsystems while they are read out.

The binary interface itself looks good. Can you do a follow-up patch to
remove struct kvm_stats_debugfs_item and avoid the duplication? I'd
rather have that too before committing the code.

Thanks,

Paolo