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Re: [Paparazzi-devel] Suggestions

From: Alexandre Bustico
Subject: Re: [Paparazzi-devel] Suggestions
Date: Fri, 13 Dec 2013 14:40:29 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0

Le 13/12/2013 14:28, Ben Laurie a écrit :
This is because the cost of context switches in RT
OSes is very high compared to the cost of function calls and
occasional timer checks...

With chibios on stm32f4, context switching @ 1khz in the worst case : using hardware float unit (so that float registers have to be saved), have a cost of 0.1%, so 99.9% for your tasks, 0,1% for the system, when you are in position where you miss theses 0.1%, you're in big trouble :-)

"big" mcu, are designed for rtos, there is dedicated timer for the systick, and dedicated hardware for making context switch easy and fast.


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