On Mon, Aug 16, 2010 at 11:07 PM, Manikandan Ramachandran <crmanik@xxxxxxxxx> 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? >> I'm not a programmer so I'll leave it to someone else to comment on the code. (If at all.) In my mind the purpose of the rt-kernel is not to 'go faster' but rather to manage the __latency__ on high priority events. I use rt-sources for my real-time audio system. I need low latency to my sound cards. With rt-sources I can set the priority of sound cards higher than other parts of the hardware system, and with the priority higher when they need to send or receive audio data it happens in a known amount of time. Without rt-sources they may want access to the system but a disk drive or the network can get in the way and cause delays. If your program is measuring time around a loop getting time of day then that's not likely a good measurement. If you measure how much the interrupt latency changes when a sound card interrupts and asks for service then that's probably more of where you'll see the value. Again, not a programmer. Cheers, Mark -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
