XScope performance figures
Data transferred from the xCORE device to the debug adapter is lossless, but data transferred from the debug adapter to your host PC may be lossy, depending on the speed of your PC.
Transfer rates between the xCORE Tile and XTAG-2
The recommended xConnect Link speed for most target hardware is 10ns between transitions (10MByte/sec). This can be achieved by setting the link interbit gap to 5 cycles (see Link). The latencies and maximum call rates for the probe functions using an xConnect Link at this speed are given in XScope performance figures for xConnect Link with 5-cycle interbit gap.
Probe function |
Latency (core cycles) |
Max calls/sec |
|---|---|---|
xscope_probe_data_pred |
15 (always) |
666,000 |
xscope_probe |
20 (with no contention) |
999,000 |
xscope_probe_cpu |
27 (with no contention) |
666,000 |
xscope_probe_data |
22 (with no contention) |
666,000 |
xscope_probe_cpu_data |
28 (with no contention) |
555,000 |
If two subsequent calls are made, the second call may be delayed in line with the maximum frequency. For example, if xscope_probe_data_pred is called twice, the second call is delayed by approximately 1.5µ s.
The maximum call rates can be increased by speeding up the link and reducing the interbit gap (see Link). A small interbit gap requires careful layout of the link, since it increases link frequency.
The UART interface executes at a rate of 2MB/s.
Transfer rates between the XTAG-2 and Host PC
Many PCs are limited to inputting trace data from the XTAG-2 at a rate of 500,000 trace records/sec or less. If your PC is unable to keep up it will drop records, reducing the granularity of the trace data. The XDE Scope view marks the loss of data on the timeline.