Книга: Microsoft Windows Embedded CE 6.0 Exam Preparation Kit

Interrupt Latency Timing (ILTiming)

Interrupt Latency Timing (ILTiming)

The ILTiming tool is particularly useful for Original Equipment Manufacturers (OEMs) who want to measure ISR and IST latencies. Specifically, ILTiming enables you to measure the time it takes to invoke an ISR after an interrupt occurred (ISR latency) and the time between when the ISR exits and the IST actually starts (IST latency). This tool uses a system hardware tick timer by default, but it is also possible to use alternative timers (high-performance counters).

The ILTiming tool relies on the OALTimerIntrHandler function in the OAL to implement the ISR for managing the system tick interrupt. The timer interrupt handler stores the current time and returns a SYSINTR_TIMING interrupt event, which an ILTiming application thread waits to receive. This thread is the IST. The time elapsed between the reception of the interrupt in the ISR and the reception of the SYSINTR_TIMING event in the IST is the IST latency that the ILTiming tool measures.

You can find the ILTiming tool's source code in the %_WINCEROOT%PublicCommonOakUtils folder on your development computer if you have installed Microsoft Platform Builder for Windows Embedded CE 6.0 R2. The ILTiming tool supports several command-line parameters that you can use to set the IST priority and type according to the following syntax:

iltiming [-i0] [-i1] [-i2] [-i3] [-i4] [-p priority] [-ni] [-t interval] [-n interrupt] [-all] [-o file_name] [-h]

Table 3-1 describes the individual ILTiming command-line parameters in more detail.

Table 3-1 ILTiming parameters

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