On Sat, Mar 14, 2009 at 10:07 PM, Leon Woestenberg <leon.woestenberg@xxxxxxxxx> wrote: > Hello Cliff, > > On Tue, Mar 10, 2009 at 1:44 PM, Cliff Brake <cliff.brake@xxxxxxxxx> wrote: >> Clarification, I don't have the RT patch applied, just CONFIG_PREEMPT >> from Linus's kernel. Reviewing my notes from several years ago, I ran >> into a similar issue and the RT patch fixed it, so now to figure out >> the best way to get a recent RT patched ARM kernel ... >> >>> timing. However, it seems that the system has trouble receiving the >>> response in a timely fashion. I often observe that it takes at least >>> 10ms for the application to receive the response data after the data >>> has appeared on the rs232 bus. Is the RT patch something that would > > We are running a real-time RS-485 protocol where the time window is 1 > ms and only under heavy load we got deadline misses > 1 ms. > Unfortunately I didn't measure the max latency then, but 10 ms sounds > like excessive latency to me. > > Under 2.6.24.7-rt24 (or whatever -rtxy in that series) we have never > missed the 1 ms deadline. Thanks Leon. I guess its pretty obvious at this point I need the RT patch. Still trying to figure out the best way to get this with 2.6.27 or later -- I really don't want to go back to 2.6.26. Thanks, Cliff -- ======================= Cliff Brake http://bec-systems.com -- 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
