Re: RE: Context Switch in Real Time Linux Vs VxWorks (or any other RTOS)

I'm sorry to say, but this document, written as a class exercise, is 
not something anyone should rely on. WindRiver has been circulating it
and I tracked down the Professor who taught the course this was 
written for and he was shocked to hear it was being cited.

If you read the paper, it doesn't actually show much evidence that anything
was tested on RTLinux at all. I am not at all sure that he tested
RTCore  itself, it looks like he used a RTLinux modified Linux and
tested Linux operations. For example, he states that priority
inheritance is implemented in RTLinux - which is not true. He says
he configured both operating systems to use round-robin, even though
RTLinxFree only implements priority scheduling. His test of context
switch time shows a high standard deviation for RTLinux, but we have
never seen similar results on any platform. His interrupt latency tests
also look like he  tested Linux and not RTCore. The lack of raw numbers
and the absence of any test code does not induce any confidence.

In sum, we have an unreviewed class project, lacking backing documentation
and containing serious mistakes. It's pretty much worthless. 



On Sat, Jul 17, 2004 at 06:46:49PM +0530, Arun Prasad Velu wrote:
> Thanks to Robert for sharing the pdf document on "Performance Analysis of
> VxWorks and RTLinux". Its worth to read, I felt. I was looking for something
> similar and the document did give some inner thoughts on what I was looking
> for.
> 
> I've found the link to download that document and here it's
> 
> http://contest.kesic.or.kr/dataroom/pdsfile/VxWorks_RTLinux_PerfomanceData.p
> df
> 
> Thought others may need it.
> 
> Regards
> Arun
> P.S. Sorry for posting the same to more than one group. I just wanted a
> quicker reply/input.
> 
> -----Original Message-----
> From: Arun Prasad Velu [mailto:[email protected]]
> Sent: Friday, July 16, 2004 10:35 AM
> To: '[email protected]';
> '[email protected]'
> Subject: Context Switch in Real Time Linux Vs VxWorks (or any other
> RTOS)
> 
> 
> Hi,
> 
> I am in the process of analyzing the feasibility of migrating an existing
> VxWorks system (MPC860 target) to Linux (RTOS).
> 
> I'd like to compare the features of Linux and VxWorks with respect to the
> Real Time capabilities. I am little concerned about Linux's Context
> Switching.
> 
> I'd like to get your opinion on this. Even if I want to move to Linux, I'll
> have to convince my management. So, any pointers on comparison of Linux Vs
> VxWorks with respect to Real Time capabilities would be highly appreciated.
> 
> Thanks and Regards
> Arun
> 
> 
> Arun Prasad Velu,
> Team Lead (Systems Software),
> Omnee System Solutions India Pvt. Ltd.,
> Abundance Networks Division,
> E-401, Crystal Plaza, New Link Road,
> Andheri (West), Mumbai - 400 053
> Tel - +91-22-5692 5159 / 2673 3299
> E-mail : [email protected]
> http://www.abundancenetworks.com
> http://www.osscorporation.com
> 
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