Investigation of Machine-specific Frame Latency Issues (PresentData)

[planetchili]

As first reported in #590, on certain machines we see frequent drops to zero on all frame data metrics in the overlay (telemetry unaffected). This has been tentatively traced back and linked to PresentData. The ETW events themselves come in with low latency, but the frames fail to be completed and output in a timely fashion by the PresentData state machinery.

pmlog.txt
pmlog-mid.txt
pmsvc-log-260305-164320.txt

Possible scenarios:

• Event sequences on some platforms differ in a way that trips up the state tracking
• Expected events were changed or removed
• Drivers or components are emitting essential events very late (seems unlikely)

First steps: capture ETL on misbehaving system concurrent with confirming behavior during capture period. If this can reproduce the dynamic query behavior on playback, it would confirm several theories and narrow down possible causes. Such ETL could then be used for system-agnostic analysis and for automated test cases to guard against such issues in the future.

[planetchili]

Dual BMG workstation showing 2000-3000ms frame lag with 12 ms avg etw latency. Also of note is the old frame latency etwq logging was barely trigger, indicating that most received frames where not of finalState=Presented

[planetchili]

Worthwhile experiment is trying on mobile with 2nd monitor attached.