On Tuesday, January 31, 2012 10:51:56 AM Ed Nisley did opine: Hi Ed;
> On Mon, 2012-01-30 at 23:35 -0500, gene heskett wrote: > > htop shows 2 cpu's with the 2nd one sitting at 0.0% use. > > As I understand it, that's the way it should be. > > The point of isolating the second CPU / core / whatever is to dedicate > it to the real-time parts of RTAI, thus reducing interrupt latency. The > CPU will sit there, completely idle, most of the time, so that when a > real-time interrupt / task needs work, it can be dispatched immediately. > > Pinning AXIS to that "idle" CPU will definitely make the UI run much > faster, but then the interrupt latency will (uh, should) get much worse, > with the usual horrible effects on software step pulse generation. > > At least, that's how I think it works... My theory, based on observations here, is that any improvement in latency's obtained by using isolcpus is the result of locking out the migration code. I suspect isolcpus=3 on a phenom like this one would not effect the latencys reported because there would still be 3 cores for the migration code left to shuffle stuff around/ By using taskset, I finally see some usage of cpu1, and latency-test is reporting less than half what it was best case without it. I've also cut the base thread time from 65000 to 25000 without causing a hint of lag yet, but that core is then up to 50% use when executing gcode. What I think I've been saying is that we didn't know how it was working, everyone was convinced we would not see rtai activity in a cpu load report because they weren't seeing any, and that by forcing the issue to match our thoughts, a relatively large improvement has been made available to us all. IOW the cpu usage report has been correct all along, none of the isolcpus marked core was ever being used. Now, with the taskset launcher, it is. And the load on cpu1 I see in htop or gkrellm is now showing us the real usage. Now the show-stopper is G38.2. It works fine, but the next machine move that breaks the probe connection aborts the whole program. :( Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> Question authority. ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
