On Thu, Aug 12, 2010 at 12:53 PM, Jeff Angielski <j...@theptrgroup.com> wrote: > On 08/11/2010 06:18 PM, Manikandan Ramachandran wrote: >> >> Hello All, >> I created a very simple program which has higher priority than >> 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. To my suprise I see >> 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. This is > important for servicing hardware. Normal users find the -rt useful for > audio/video applications. Engineering 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 space, > you'd be better off using the non-rt variants. > > > -- > Jeff Angielski > The PTR Group > www.theptrgroup.com > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev >
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 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
