EBo wrote: > Steve (and others), > > I was finally able to get it to configure similar to Eric's setup (althought I > am running 2.6.27-magma due to problems with the 2.6.24 kernel not playing > nicely with my CPU fan -- a known problem), but have an odd thing which seems > to require a CPU hog process in another terminal. If the process is not > there, then the RT thread seems to stall waiting for the scheduler to give it > a time slice.
How long of a stall? In my experience, the "cpu hog" is able to reduce latencies from 10-20 microseconds down to perhaps 5-7uS. If your stalls are much longer than that you must be seeing something new. My own theory (and it is only a theory) about why the cpu hog works is related to cache. The hog uses very little memory, and since it keeps one CPU busy, that CPU never runs any other code. So the RT code doesn't get flushed out of cache, and doesn't have to get fetched back into cache later. I saw some other cache related behavior a long time ago when doing some latency testing. The latency results improved noticeably when I lowered the thread period below some threshold. (I don't remember the threshold period, it was at least a year ago.) I eventually realized that when I was running the thread very frequently, the RT code never got pushed out of cache. When I increased the period, other processes had enough time to replace the RT code in cache between invocations of the thread. Regards, John Kasunich ------------------------------------------------------------------------------ Create and Deploy Rich Internet Apps outside the browser with Adobe(R)AIR(TM) software. With Adobe AIR, Ajax developers can use existing skills and code to build responsive, highly engaging applications that combine the power of local resources and data with the reach of the web. Download the Adobe AIR SDK and Ajax docs to start building applications today-http://p.sf.net/sfu/adobe-com _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
