Goal

VMware provides esxtop, a tool customers use to analyze the storage performance of a VM. The CNV team would like OCP-V customers to have a similar tool. While basic throughput/IOPS metrics exist, we cannot easily diagnose latency outliers (e.g., "how many IOs took >X ms?").

QEMU already supports block-latency-histogram-set, which allows defining latency thresholds and counting IOs within such bins. However, libvirt currently does not expose an API to configure these histograms, nor does it retrieve this histogram data in the domain statistics.

Old patch attempt xref: https://lists.libvirt.org/archives/list/devel@lists.libvirt.org/thread/FUWPV5RLSECPKLMXUBYIDBSXNDL6NWCY/?sort=date

Acceptance criteria