Embedded Target for Texas Instruments C6000 DSPs

Definitions of Report Entries

In the following sections, we provide definitions of the entries in the profile report. These definitions help you decifer the report and better understand how your process is performing.

Critical Headroom

The measured amount of time, in CPU cycles, the CPU spent in idle mode during the worst-case interrupt cycle, when all rates in the code coincide and the code exhibits the maximum measured number of clock cycles spent in idle mode (time the CPU spends waiting to process information). When critical headroom approaches zero, your code is at risk for overrunning. Interpret critical headroom as a portion of the time between interrupts.

Time Between Interrupts

Time in microseconds between interrupts, where the interrupt is generated either by the ADC block or by a PRD timer object.

Number of Interrupts Counted

The number of interrupts that occurred between the start of model execution and the moment the statistics were obtained.

CPU Clock Speed

The instruction cycle speed of your digital signal processor. On the C6701 EVM, you can adjust this speed to one of four values, where 100 MHz is the default--25, 33.25, 100, 133 MHz. If you change the speed to something other than the default setting of 100 MHz, you must specify the new speed in the Real-Time Workshop options. Use the Current C6701EVM CPU clock rate option on the TIC6000 runtime category on the RTW tab.

Set at a fixed 150 MHz, you cannot change the CPU clock rate on the C6711 DSK. You do not need to report the setting in the Real-Time Workshop options.

CPU Load

The average CPU usage computed by CCS. Note that the actual load in any particular interrupt cycle may vary greatly from this average, especially in multirate applications.

Maximum Time Spent in This Subsystem per Interrupt (Max Time)

The amount of time spent in the code segment corresponding to the indicated subsystem in the worst case. Over all the iterations measured, the maximum time that occurs is reported here. Since the profiler only supports single-tasking solver mode, no calculation can be preempted by a new interrupt. All calculations for all subsystems must complete within one interrupt cycle, even for subsystems that execute less often than the fastest rate.

Maximum Percent of Interrupt Interval (Max %)

The worst-case execution time of the indicated subsystem, reported as a percentage of the time between interrupts.

STS Objects

Profiling uses STS objects to measure the execution time of each atomic subsystem. STS objects are a feature of the DSP/BIOS run-time analysis tools, and one STS object can be used to profile exactly one segment of code. Depending on how Real-Time Workshop generates code for each subsystem, there may be one or two segments of code for the subsystem; the computation of outputs and the updating of states can be combined or separate. Each subsystem is assigned a unique index, i. The name of each STS object helps you determine the correspondence between subsystems and STS objects. Each STS object has a name of the form

• stsSysi_segment
  

where i is the subsystem index and segment is Output, Update, or OutputUpdate.

Reading Your Profile Report

Profiling Your Generated Code