Task switch time in m52259 and MQX 3.8

[same]

Hi,

I have a m52259 board and MQX 3.8 on it.

I want to know how long is the context switch time between tasks.

I have multiple small tasks, and every task at end of its code will make another task ready and make itself suspended. But I strongly need to know the context switch time.

is there anyone know it?

Thanks everybody

[same]

I found it here:    https://community.freescale.com/message/107966#107966

thanks DavidS

System Parameters

Context Switch	4.30us 413.12us 1MHz	Service Interrupt and return to task	1.51us 145.40us 1MHz
System Timer/Tick Overhead	2.52us 242.40us 1MHz

---

Task Management

Create Task	51.02us 4.90ms 1MHz	Delete Task	174.00us 16.70ms 1MHz
Block Task	4.30us 413.12us 1MHz	Ready Task	3.73us 358.32us 1MHz
Yield Task	6.73us 646.32us 1MHz

---

Task Queues

Suspend Task	16.78us 1.61ms 1MHz	Suspend Task Context Switch	7.91us 758.96us 1MHz
Resume Task	6.19us 594.32us 1MHz	Resume Task Context Switch	10.48us 1.01ms 1MHz

[TomE]

Measure it.

I always set up a spare 16 or 32 bit hardware timer running at 1MHz. On the MCF5329 I'm using, that's one of the DMA Timers. Then any code can read "the current time in microseconds" either side of a function, event or task. It can print it, store it in a variable (for inspection in the debugger), accumulate, log or whatever you want to do.

Of course the simplest thing is to turn a LED on that is connected to a hardware pin at point "A" in your code and turn it off at point "B". You then measure the time with an oscilloscope. Make sure to measure the overhead of turning the LED on and off, as on some hardware ports it can be surprisingly slow. I've worked on a non-Freescale CPU that took 200 or more CPU clocks to write to a GPIO pin!

Tom