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

Jing Zhang
2021-06-11T13:41:04Z

Hi Paolo,

On Fri, Jun 11, 2021 at 8:35 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> 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
>
Sure. Will do.

Thanks,
Jing