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Study of FreeRTOS: a document

Posted by dcgirish16 on December 2, 2013

Came across a paper on FreeRTOS. Though this paper is a old one, an outcome of study of FreeRTOS of version around 4.0 in 2007, wanted to know if the conclusions at the end of the document made are acceptable and if yes, has the newer versions of FreeRTOS has changed from what is concluded in the document else, the market is accepting the FreeRTOS as is..

below is the link of the paper.

http://www.mikrocontroller.net/attachment/95930/FreeRTOSPaper.pdf

Thanks, Girish


Study of FreeRTOS: a document

Posted by rtel on December 2, 2013

I have not seen this before - it is a giggle ;O)

"No mechanisms to counter priority inversion are implemented."

Mutexes include a priority inheritance mechanism. So that is not true - maybe it was when it was written.

"Overall, FreeRTOS was determined to be slightly too feature-rich for limited resource embedded devices"

That contradicts the authors other assertions that it could do with including both a priority inversion and a deadlock prevention scheme - which would of course make it more feature rich. It is in fact massively more feature rich now than when the paper was written. Especially with the introduction of event groups/flags and a centralised deferred interrupt mechanism in the soon to be released V8.

"FreeRTOS implements co-routines. These are not considered in this document as they are duplicative of the existing functionality"

This also contradicts other statements, as co-routines are (were) designed specifically for the tiny platforms.

I'm afraid I didn't read the rest, just a few snippets, but wonder why you are reading a really old document like that rather than the wealth of up to date information that is freely available to you?

Regards.


Study of FreeRTOS: a document

Posted by dcgirish16 on December 3, 2013

Hi Real Time Engineering Ltd., Thanks for the quick response.
>>>> "but wonder why you are reading a really old document like that rather than the wealth of up to date information that is freely available to you?"

I am going through the material what ever is available on the net to understand more about OS concepts and the way they are implemented/evolved. in fact, for one of the questions raised on linked-in FreeRTOS group regarding "Priority Inversion", I responded with the answer what you mentioned here and referring to the FreeRTOS link where this is described:-).

One thing this document attracted me is the way the OS is dissected. explaining the importance of most of structures and how they are used; which gave a little more insight into the OS but got little confused with the conclusions. Hence, wanted to confirm if, what ever the study done is in the right way and the results of this study were/are true/not true though the document is old.

in fact, there is one more document floating around comparing eCos with FreeRTOS.

any ways, Thanks a lot again for the patience and respnse.

Thanks, GCD


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