Sources of Additional Latency - 4.1 English

Soft Error Mitigation Controller Product Guide (PG036)

Document ID
PG036
Release Date
2022-05-04
Version
4.1 English

It is highly desirable to avoid throttling on the Monitor Interface, because it increases the total error mitigation latency:

After an attempted error correction, but before exiting the error correction state (at which time the correctable status flag is updated), the controller issues a detection and correction report through the Monitor Interface. If the MON Shim transmit FIFO becomes full during this report generation, the controller dwells in this state until it has written the entire report into the MON Shim transmit FIFO. When this happens, the error correction latency increases.

After classifying an error, but before exiting the error classification state (at which time the essential status flag is updated), the controller issues a classification report through the Monitor Interface. If the MON Shim transmit FIFO becomes full during this report generation, the controller dwells in this state until it has written the entire report into the MON Shim transmit FIFO. When this happens, the error classification latency increases.

The approaches to completely eliminate the potential bottleneck are to remove the MON Shim and leave the Monitor Interface unused, or use the Monitor Interface with a peripheral that never signals a buffer full condition. In the event the Monitor Interface is unused, the Status Interface remains available for monitoring activity.

For peripherals where the potential bottleneck is a concern, it can be mitigated. This is accomplished by adjusting the transmit FIFO size to accommodate the longest burst of status messages that are anticipated so that the transmit FIFO never goes full during error mitigation.

If a transmit FIFO full condition does occur, the increase in the total error mitigation latency is roughly estimated as shown in This Equation .

Equation 2-5 pg036_product_spec00010.jpg

In This Equation , MessageLength-BufferDepth is in message bytes, and the Transmission Rate is in bytes per unit of time.