Basic timing parameters for KADAK's AMX Multitasking Kernel are listed below. All timing figures are for guidance only and are not to be interpreted as product specifications.

Measurement Interpretation

The task switch time is the time taken by AMX to suspend one task and resume execution within another. The measurement is made as follows. A high priority task waits for a signal from a low priority task. The low priority task runs, generates the signal and is immediately blocked because of the switch back to the high priority task. The task switch time is derived by averaging 100 such cycles.

Interrupt latency is the time taken by the processor to respond to an interrupt request from a device seeking service. The time is measured from the instant the external interrupt signal is generated through to the point at which the processor has decoded the request and branched to a software handler.

The worst case interrupt latency occurs when the application disables interrupts, thereby inhibiting the processor from responding to an interrupt. The interrupt latency figures quoted are the worst case scenarios possible within AMX. In all instances, the worst case occurs in a path through AMX with a very low probability of execution. Despite this, we publish it!

Handler latency time is the time taken by the AMX Interrupt Supervisor to reach an application interrupt handler coded in C. This standard C function is free to use a variety of AMX services including semaphore signalling and message passing. For RISC processors like the PowerPC and ARM which do not automatically identify each interrupt source, the measurement includes the time taken by AMX to call an application dependent interrupt identification procedure.

Additional Materials

	Be sure to read the comprehensive timing booklet. It provides an introduction to the timing issues which you will encounter using any RTOS. It discusses some of the factors which make timing measurement so difficult and helps to explain why instruction counts and cycle counts can rarely be used to measure execution times.
	You can also download the AMX Timing Guide. Although it duplicates some of the information in the timing booklet, it also provides specific timing metrics for frequently occurring AMX operations.

Basic AMX Timing Parameters

Available Timing Data Sheets

An AMX Timing Guide is included with each AMX Reference Manual. The guide defines the AMX application task scenarios which were used to measure specific features of AMX such as clock service, task synchronization and message passing.

For each target processor for which measurements are available, the AMX Timing Guide provides a Timing Data Sheet. The data sheets define the processor, the memory configuration, the cache conditions and the C compiler features used. The data sheets summarize the timing results and provide additional explanatory notes when deemed appropriate.

Timing data sheets are available for each of the processors listed in the following tables. KADAK regrets that it cannot provide timing data for every processor operating at all possible frequencies with each of the supported toolsets.

A copy of the AMX Timing Guide containing these timing metrics is available for downloading.

	Available AMX 86 Timing Data
	25 MHz		Intel486 SX		Commercial PC
	40 MHz		AMD Am186ES		AMD Net186 Demonstration Board
	24 MHz		VA Turbo186		VAutomation iCON186 Evaluation Board
	Available AMX 386/ET Timing Data
	100 MHz		Pentium		Commercial PC
	50 MHz		Intel486		Commercial PC
	Available AMX 68000 Timing Data
	25 MHz		MC68EC040		Motorola MC68EC0x0 Integrated Development Platform
	16 MHz		MC68332		GreenSpring Computer's Platform332
	25 MHz		MC68360		Motorola M68360QUADS Application Development System
	Available AMX ColdFire Timing Data
	54 MHz		MCF5206e		Motorola M5206EC3 board (Cadre III)
	132 MHz		MCF5249		Motorola M5249C3 board
	66 MHz		MCF5272		Motorola M5272C3 board
	90 MHz		MCF5307		Motorola SBC5307 board (Arnewsh)
	150 MHz		MCF5407		Motorola M5407C3 board
	Available AMX PowerPC Timing Data
	66 MHz		PPC403GCX		IBM 403 EVB Evaluation Board
	66 MHz		MPC603		Motorola Ultra 603 motherboard platform
	200 MHz		PPC405GP		IBM PPC405GP Reference Board
	Available AMX ARM / Thumb Timing Data
	20 MHz		ARM7TDMI		ARM Development Board (ARM7TDMI Version)
	32 MHz		AT91M42800A		Atmel AT91EB42 Evaluation Board
	80 MHz		ARM966E		ARM Integrator/AP Board
	600 MHz		XScale 80321		Intel IQ80321 Evaluation Platform
	Available AMX MIPS32 Timing Data
	80 MHz		MIPS 4Kc		MIPS Malta 4Kc Development Board