Throttle NICo BMC Access Based on BMC Proxy Call Latency SLO

[zhaozhongn]

As part of the DSX DPS requirements, DPS's BMC proxy calls need to satisfy certain configurable SLO. When SLO cannot be reached, NICo-wide BMC access parallelism and rate need to be throttled.

1. Define a configurable BMC proxy call latency threshold SLO (either a target value, or a target range)
2. Identify and consolidate NICo-wide BMC access points and throttling mechanism.
3. Measure BMC proxy call latency and compare against the SLO.
4. If SLO cannot be reached over a certain period of time, dial down the BMC access parallelism and/or rate, within a predefined scope and in large steps, until SLO can be satisfied.
5. If SLO has been met with large enough buffer over a certain period of time, restore the BMC access parallelism and / or rate, within a predefined scope and in small steps, until SLO buffer is no longer large enough.

[yoks]

Impossible for 2.2, depends on all components go through proxy which 2.3 ETA.