2.2.2. Priority Scrubbing
The EDC operation for the priority sectors and non-priority sectors run in parallel when priority scrubbing is enabled. The sectors in group 0 of both the priority sectors and non-priority sectors run the EDC process at time T0. This is followed by the EDC operation of sectors in group 1 of both the priority sectors and non-priority sectors at time T1, sectors in group 2 at time T2, followed by the sectors of the remaining group until the last available group. This corresponds to 1 complete cycle of the EDC process.
For an Intel® Stratix® 10 device with a total of 25 sectors and the maximum number of sectors allowed to run EDC concurrently, Smax = 2, Intel® Quartus® Prime will determine the number of groups for the priority sectors, GP and non-priority sectors, GN based on the number of priority sectors, P and non-priority sectors, N. Within GP, there is at most Smax-1 number of sectors allocated so that there is at least one sector slot left for the normal sector to run concurrently.
If P≤Smax-1, then GP = 1 and GN is determined by allocating N to the vacant sector slots. For example, P+N = 25, where P = 1 and N = 24, as shown on the left side of the following figure. Since P≤Smax-1, then GP = 1. One sector is occupied by the priority sectors and another sector slot is occupied by the non-priority sectors. GN = 24, is determined by allocating N into one sector slot. The priority sectors only need one unit of time to complete the EDC process compared to the non-priority sectors which need 24 units of time.
If P>Smax-1, then GP and GN are determined by allocating P equally into Smax-1 and N to the last vacant sector slot. For example, P = 4 and N = 21 as shown on the right side of the following figure. Since P>Smax-1, then GP = 4 where the priority sectors are divided equally. One sector slot is occupied by the priority sectors and another sector slot is occupied by the non-priority sectors, resulting in GN = 21. The priority sectors only need four units of time to complete the EDC process compared to the non-priority sectors which need 21 units of time.
With priority scrubbing, priority sectors will undergo more frequent SEU detection and correction compared to non-priority scrubbing. This provides faster SEU detection and correction for critical design modules. The interval time for priority sectors is always the minimum interval that the Intel® Stratix® 10 device is capable of, regardless of the user setting of the Minimum SEU Interval in Device and Pin Options. For example, the interval time for one priority sectors is always 1800 microseconds regardless if the Minimum SEU Interval is set to 0 or 10000 microseconds.
A warning message is prompted in Intel® Quartus® Prime when P exceeds a certain threshold which causes the priority sectors to require a longer time to complete one cycle of EDC process compared to the non-priority sectors.
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