On Thu, Aug 12, 2010 at 12:53 PM, Jeff Angielski [off-list ref] wro=
te:

On 08/11/2010 06:18 PM, Manikandan Ramachandran wrote:

quoted

Hello All,
=C2=A0 =C2=A0 I created a very simple program which has higher priority =

than

quoted

normal tasks and runs a tight loop. Under same test environment I ran
this program on both non-rt and rt 2.6.33.5 kernel. =C2=A0To my suprise =

I see

quoted

that performance of non-RT kernel is better than RT. non-RT kernel took
3 sec and 366156 usec while RT kernel took about 3 sec and 418011
usec.Can someone please explain why the performance of non-rt kernel is
better than rt kernel? From the face of the test result, I feel RT has
more overhead,Is there any configuration that I could do to bring down
the overhead?

Your "surprise" is due to your definition of "performance".

The purpose of the -rt kernels is to reduce the kernel latency. =C2=A0Thi=

s is

important for servicing hardware. =C2=A0Normal users find the -rt useful =

for

audio/video applications. =C2=A0Engineering and scientific users find the=

 -rt

beneficially for servicing hardware like sensors or control systems.

If you are just trying to run calculations as fast as you can in user spa=

ce,

you'd be better off using the non-rt variants.


--
Jeff Angielski
The PTR Group
www.theptrgroup.com
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true, in most cases non-rt will have better performance/throughput,
while rt's major goal is to have better latency for high priority
tasks. also true is that, rt kernel will have more overhead.

xianghua